Best Onion Tart Recipes

TARTE FLAMBEE (ALSATIAN BACON & ONION TART)

Steps:

• Place bacon in a skillet and cook over medium-high heat until cooked but not crisp and fat has rendered out, about 8 minutes. Drain in a strainer; reserve the fat.
• Place skillet back over medium heat. Add sliced onions. Cook briefly just until they lose their raw edge and soften up slightly, 3 to 5 minutes. Add a teaspoon or 2 of bacon fat if pan seems too dry. Remove skillet from heat and allow to cool to room temperature.
• Mix fromage blanc, creme fraiche, nutmeg, salt, black pepper, and cayenne pepper together in a mixing bowl.
• Place 1 ball of pizza dough on a well-floured surface. Flatten and roll out to a 10- or 12-inch thin circle. Transfer to a cold cast iron pan. Heat over medium-high heat to pre-cook the bottom of the crust. As dough heats and bubbles appear, deflate them with the tines of a fork so crust ends up thin and crisp (not chewy). When bottom is nicely browned and just about to start getting charred, 5 to 7 minutes, remove from heat. Repeat with remaining dough.
• Spread a generous amount of cheese mixture over the crust. Top evenly with some onions and then the bacon. Broil 5 or 6 minutes until edges are browned and starting to lift. Repeat for remaining tartes.

CARAMELIZED ONION, MUSHROOM AND GOAT CHEESE TART

Steps:

• Preheat oven to 400 degrees F.
• Using a mandolin or super-sharp knife, cut onion into paper thin slices. Clean and slice the mushrooms.
• Heat 1 tablespoon oil in a skillet over medium heat; add onion and saute until caramelized. Transfer to a bowl and set aside. Heat remaining teaspoon of oil in skillet over medium-high heat. Add mushrooms and saute until they release all their liquid and most of it boils away, should take about 5 minutes. Combine caramelized onions with mushrooms and saute together briefly; season with salt and pepper. Remove the pan from heat.
• Unfold puff pastry onto a floured surface; cut in half lengthwise to form 2 long rectangles. Gently roll out each rectangle to approximately 5 by 14 inches and place on cookie sheet. Trim edges by 1/4-inch strips all around; set strips aside. Break 1 egg into a small bowl; beat slightly. Brush edges of pastry with some of the egg. Use trimmed strips to make a raised border on each. Brush entire surface with remaining beaten egg. Prick the interior of pastry all over with a fork. Bake until pale gold, about 10 minutes. If pastry has puffed up inside edge, press it down gently. Set aside.
• Meanwhile, combine remaining eggs with 6 ounces goat cheese and blend until smooth. Spread the mixture onto pastry. Return to oven and bake just until set, about 4 minutes. Add the thyme to the mushroom mixture. Remove cookie sheet from oven and spread with thyme-mushroom mixture. Crumble remaining cheese on top. Just before serving, broil tarts on low heat for 2 to 3 minutes, until tarts are warm and cheese softens.

ALSACE ONION TART

Steps:

• Make pastry:
• Blend together flour, butter, shortening, and salt in a bowl with your fingertips or a pastry blender (or pulse in a food processor) just until most of mixture resembles coarse meal with some small (roughly pea-size) butter lumps. Drizzle evenly with 4 tablespoons ice water and gently stir with a fork (or pulse in processor) until incorporated.
• Squeeze a small handful: If it doesn't hold together, add more ice water, 1/2 tablespoon at a time, stirring (or pulsing) until just incorporated, then test again. (Do not overwork mixture, or pastry will be tough.)
• Turn out mixture onto a lightly floured surface and divide into 6 equal portions. With heel of your hand, smear each portion once or twice in a forward motion. Gather dough together with pastry scraper and press into a ball, then flatten into a disk. Chill dough, wrapped in plastic wrap, until firm, at least 1 hour.
• Roll out dough on a floured surface with a floured rolling pin into a 14-inch round and fit into tart pan. Trim excess dough, leaving a 1/2-inch overhang, then fold overhang over pastry and press against side to reinforce edge. Lightly prick bottom with a fork and chill until firm, about 30 minutes.
• Put oven rack in middle position and preheat oven to 400°F.
• Line chilled shell with foil and fill with pie weights. Bake until pastry is set and pale golden along rim, 15 to 20 minutes. Carefully remove foil and weights and bake shell until golden all over, 10 to 15 minutes more. Transfer shell to a rack. (Leave oven on.)
• Prepare filling while shell bakes:
• Cook bacon in a 12-inch nonstick skillet over moderate heat, stirring occasionally, until crisp, 6 to 8 minutes. Transfer bacon with a slotted spatula to paper towels to drain and pour off bacon fat. Add butter to skillet and cook onions with 3/4 teaspoon salt and 1/2 teaspoon pepper over moderate heat, stirring, until just wilted, about 2 minutes. Cover surface of onions with a round of parchment or wax paper (or cover skillet with a tight-fitting lid) and continue to cook, lifting parchment to stir frequently, until onions are very soft and pale golden, about 20 minutes. Stir in bacon, then remove from heat and cool 10 minutes.
• Whisk together crème fraîche, eggs, nutmeg, remaining 1/2 teaspoon salt, and remaining 1/2 teaspoon pepper in a large bowl, then stir in onions.
• Fill and bake tart:
• Pour filling into tart shell, spreading onions evenly, and bake until filling is set and top is golden, 25 to 35 minutes. Serve warm or at room temperature.

BACON, ONION AND CHEESE TART

Steps:

• Preheat the oven to 425 degrees F. Line 2 sheet pans with parchment paper.
• In a medium saute pan, cook the bacon over a medium-low heat until it begins to render, 3 to 5 minutes. Add the onions and cook until they begin to soften, about 3 minutes. Season with pepper. Set aside to let cool. Add the thyme to the cooled bacon-onion mixture.
• In a bowl, combine the farmer's cheese, creme fraiche, egg yolk and salt and pepper to taste. Set aside.
• Flour a flat surface and place the puff pastry on top. Flour the top and gently roll into a 13-by-18-inch rectangle. Cut the pastry in half and transfer each to a lined sheet pan. Using a fork, dock the puff pastry (pierce it slightly with the tines), leaving a 1-inch border untouched.
• Divide the cheese mixture between the two sheets of pastry and spread evenly on the docked area. Top each tart with half of the bacon-onion mixture.
• Place the tarts in the oven on the lower racks and bake, rotating halfway through, until the crusts are dark golden, about 25 minutes. Garnish with the pecorino and chives.

ONION TART

Steps:

• Blend flour and salt in the bowl of a food processor. Scatter butter over flour, top with lid and pulse 12 pulses to cut butter into flour to a coarse meal consistency.
• Dump butter-flour mixture into a medium stainless bowl. Make a well in the center and pour ice-cold water into the well.
• Using a flexible plastic dough scraper instead of your warm hands, bring the dough together by folding and pressing. Be firm and brisk and get the dough past its shaggy stage into a neat disk, trying to avoid using your hands or too much kneading. Refrigerate the dough for 30 minutes. Heat the oven to 375 degrees.
• Meanwhile, cut the onions in half and peel them. Slice the halves with the ribs (root end to sprout end direction), not against, to create julienne slices rather than half moons.
• In a wide sauté pan over medium-low heat, melt the bacon fat and slowly sweat the onions until they are caramelized. Take all the minutes you need - 25 or so - to let them soften to translucent, then to let the water they release start to evaporate, then to allow the sugars they contain to start to brown in the pan, so that you end up with soft, sweet and evenly browned onions. This is achieved by a slow caramelization. Set onions aside to cool.
• Roll tart dough out to a 1/4-inch-thick round, and drape over a round 10-inch fluted false-bottom tart pan. Lay dough into the pan, gently pressing into the bottom, and roll the pin across the pan to cut off the excess dough. Use your fingers to press the edges into the flutes, accentuating the shape of the dough edge. Dock the bottom of the dough with the tines of a fork, weight the pastry with beans or weight and blind-bake for 25 minutes.
• In a bowl, beat the egg with the cream. Stir in the caramelized onions. Season with pepper, nutmeg and salt to taste. Stir well, and make sure the onions are all evenly coated with the custard.
• Remove tart shell from oven, and slip it onto a baking sheet. Remove weights, fill with the onion-custard mixture and distribute it evenly. Return tart to oven on the sheet, and bake for 25 minutes, or until custard has set, the tops of the onions start to achieve a deeper brown and the dough is dark golden brown at the edges.
• Remove from the ring, and allow to cool just a few minutes on the rack, so that the piping hot tart shell can kind of tighten up enough to be sliced with a sharp chef's knife. (In the first few minutes straight out of the oven, the dough is kind of soft from the heat, possibly giving you the false impression that you have a soggy tart. Let it sit on the rack just to shake off this initial soft stage and to recrisp and refirm, which it will.) Cut into wedges, and serve while hot.

CARAMELIZED ONION POTATO TART

Steps:

• Preheat oven to 350 degrees F.
• Set a large skillet over medium heat and add 4 tablespoons of olive oil. Add sliced onions and cook over medium heat for 10 to 12 minutes until they are tender and brown all over.
• Using a mandolin (or sharp knife), finely slice the potatoes into rounds (you can place them in a bowl with a wet towel over the top to stop them from going brown while you work). Place the potatoes into a bowl and season with salt and pepper. When ready, add the onions and toss to combine without breaking potatoes.
• Add about 1 tablespoon water to the same pan the onions were cooked in and allow it to come to a bubble. Using layered paper towels, wipe the pan clean.
• Add some extra-virgin olive oil to the pan and add the potatoes to the pan, making sure the potatoes are flat. Top with the diced butter.
• Take a piece of parchment paper and fold in half. Find the middle of the parchment along the crease and hold in place with your finger. Taking the right side of the parchment, pull it towards the center and fold it straight down to create a diagonal edge. Fold the parchment in half to create a triangle. Place the pointed edge in the middle of the saute pan on top of the potatoes to find its radius. Make a marker of where the pan edge ends (or starts). At this point you can cut the parchment at this marker and open to reveal a circle.
• Cover the potatoes with the parchment paper and press down. Drizzle some extra-virgin olive oil over the top so it down burn and rub it in.
• Place the pan into the oven on the top rack and bake for about 45 minutes.
• When done remove from oven and run a knife around the edge to separate from the pan. Place a large plate on top of the saute pan and flip. Remove the saute pan. Allow to cool slightly before cutting into slices.

CARAMELIZED ONION TART

Steps:

• Thaw the pastry sheet at room temperature for 40 minutes or until it's easy to handle. Heat the oven to 400 degrees F. Line a baking sheet with parchment paper or spray with vegetable cooking spray.
• Heat the oil in a 12-inch skillet over medium heat. Add the onion and cook for about 15 minutes or until golden, stirring often. Season to taste and let cool.
• Unfold the pastry sheet on a lightly floured surface. Roll into a 12-inch square. Place on the prepared baking sheet. Brush the edges of the square with water. Fold over the edges 1/2 inch on all sides, pressing firmly with a fork to form a rim. Prick the pastry thoroughly with a fork.
• Spread the onion mixture over the pastry crust. Top with the gruyere and parmesan cheeses and sprinkle with the chives.
• Bake for 20 minutes or until golden and bubbly. Cool for 5 minutes on a wire rack. Cut into approximately 3 x 2-inch rectangles. Serve warm.

TOMATO & CARAMELISED ONION TART TATIN

Steps:

• Heat the butter and oil in a frying pan until the butter has melted. Cook the onion over a medium heat for about 10 minutes until beautifully golden, stirring often. Stir in the sugar and cook for another couple of minutes. Tip the onion and juices into a bowl and set aside. Preheat the oven to 200C/gas 6/fan 180C.
• For the pastry, rub the butter into the flour to make fine crumbs. Stir in the parmesan, thyme and a pinch of salt. Add the egg yolk and 2 tbsp cold water, then mix to make a dough. Wrap in cling film.
• For the tomatoes, heat the butter and oil in a 20cm tart tatin tin on the hob until quite hot. Stir in the sugar and garlic, then put in the plum tomatoes cut-side down with a few thyme sprigs, and sizzle for no more than 1 minute. Scatter in the whole cherry tomatoes and tuck in a bit more thyme. Take off the heat and spread the onions on top. Season with salt and pepper.
• Roll out the pastry until it's slightly bigger than the top of the tin. Lay it over the onions and tuck any excess down the sides.
• Bake on a baking sheet for 25 minutes until golden. Cool for 5 minutes, invert a plate over the top and upturn the tart onto it. Scatter with extra thyme and black pepper.

TOMATO, GOAT CHEESE, AND ONION TART

Steps:

• Preheat oven to 375°F.
• If necessary, roll out dough on a lightly floured surface into an 11-inch round and fit into tart pan. Trim excess dough, leaving a 1/2-inch overhang, then fold overhang inward and press against side of pan to reinforce edge. Lightly prick bottom and sides with a fork.
• Line tart shell with foil and fill with pie weights. Bake in middle of oven until pastry is pale golden around rim, about 20 minutes. Carefully remove weights and foil and bake until golden all over, 8 to 10 minutes more. Cool in pan on a rack.
• While tart shell is baking, heat 2 tablespoons oil in a 12-inch heavy skillet over moderate heat, then cook onion with salt and black pepper to taste, stirring frequently, until golden brown, 15 to 20 minutes.
• Preheat broiler.
• Spread onion over bottom of tart shell and top with 1 rounded cup goat cheese. Arrange tomatoes, slightly overlapping, in concentric circles over cheese. Sprinkle with remaining cheese and salt and pepper to taste and drizzle with remaining tablespoon oil. Put foil over edge of crust (to prevent overbrowning).
• Put tart pan on a baking sheet and broil tart about 7 inches from heat until cheese starts to brown slightly, 3 to 4 minutes.

ULTIMATE ONION TART

Steps:

• Heat oven to 190C/fan 170C/gas 5. Roll out the pastry on a lightly floured surface and use to line a deep 23cm fluted flan tin. Line with baking paper and fill with baking beans. Bake blind for 15 mins.
• Heat the butter and oil in a large frying pan, then gently fry the onions, covered, for about 30 mins until completely softened, but still pale in colour.
• Beat the eggs and cream together in a bowl, then add the cheese and some seasoning. Stir in the onions, then spoon the mixture into the flan case. Bake for 25-30 mins until lightly set and browned.

CARAMELISED ONION TART

Steps:

• Heat oven to 190C/fan 170C/gas 5. Slide a baking sheet in to heat. Roll the pastry out enough to line a deep 20cm flan tin or a shallow 23cm one. Chill for 10 mins.
• Put a few balls of crumpled foil in the base of the pastry case and bake on the baking sheet for 10 mins. Remove the foil and bake for 5 mins more, until light golden.
• Meanwhile, cook the onions in the oil until starting to soften, then add thyme, pepper, and salt if you want to. Cook slowly for about 15 mins until the onions are soft and tinged brown.
• Beat the eggs, beat in the milk and half the cheese and some pepper. Spread the onions over the flan case and pour in the egg mix. Sprinkle the remaining cheese on top and bake the tart on the baking sheet for 30-40 mins until the filling is firm and golden, and the pastry crisp. Serve warm or cold.

ONION TART

Steps:

• Preheat oven to 350 degrees F (175 degrees C).
• In a large skillet, melt butter and saute onions until soft. Remove from heat. Place bacon in a large, deep skillet. Cook over medium high heat until evenly brown. Drain, crumble and set aside.
• Mix in eggs.
• Pour into prepared shell and bake at 350 degrees F (175 degrees C) for approximately 20 minutes. Top with bacon, Can be served warm or cold.

FRENCH ONION TART

Steps:

• Preheat the oven to 400 degrees F. Line a baking sheet with parchment paper.
• On a work surface, roll the puff pastry into a roughly 10 by 16-inch rectangle. With a sharp knife, trim uneven edges to make a perfect rectangle. Evenly cut off the outer 1 inch of each side of the rectangle in strips; put the puff sheet on the baking sheet. Dip your finger in water and run around the top edges of the rectangle and replace the removed strips of pastry along the edges of the sheet, pressing lightly to adhere. With a fork, pierce the interior of the tart shell to prevent rising; do not pierce the adhered edges. Bake until the outer edges have puffed and are golden in color; about 15 minutes. Set aside.
• Heat 2 tablespoons olive oil in a large skillet over medium-low heat. Add onions and thyme sprigs and season well with salt and pepper, to taste. Cook, stirring occasionally, until the onions begin to brown. Add the stock, a tablespoon at a time, as the pan gets dry, scraping and stirring the brown bits that are stuck to the bottom oft the pan. When the onions are caramelized to a dark golden color, remove from the heat and discard the leafless thyme sprigs (the leaves fall off while cooking).
• When ready to serve, preheat the oven to 350 degrees F. Evenly spread the caramelized onions on the cooked pastry shell and heat in the oven until warmed through, 5 to 7 minutes. Remove from oven, to a cutting board and cut into wedges. Arrange on a serving platter and garnish each wedge with a sprig of fresh thyme. Serve immediately and enjoy!

ONION TART

Steps:

• Line unpricked pastry shell with a double thickness of heavy-duty foil. Bake at 450° for 8 minutes. Remove foil; bake 5 minutes longer. Cool on a wire rack. , In a small skillet, saute onions in oil until tender; cool. In a food processor, combine the eggs, feta cheese, salt, pepper, nutmeg and hot pepper sauce; cover and process until smooth. Gradually add cream and milk; process until blended., Brush the inside of crust with mustard. Sprinkle the green onions, chives and sauteed onions over crust. Carefully pour egg mixture over onions. Top with Parmesan cheese. , Bake at 375° for 30-40 minutes or until a knife inserted in the center comes out clean.

CHEESEBOARD & ONION TART

Steps:

• Put the flour, butter and salt into the bowl of a food processor, then pulse until the mix looks like fine crumbs. Splash in 4 tbsp cold water, then pulse to a dough. Turn onto a lightly floured surface, shape into a smooth disc, then wrap and chill for at least 10 mins. Heat oven to 200C/fan 180C/gas 6.
• Roll pastry out on a floured surface until large enough to line a 23cm loose-bottomed tart tin. Line the tin with the pastry, leaving any excess pastry overhanging. Line with baking paper, then fill with baking beans. Bake on a baking sheet for 15 mins. Take out the paper and beans, then bake for 10 mins more until pale golden and cooked. Use a serrated knife to trim the pastry level with the tin - resting the knife flat on the edge of the tin will help achieve an even finish.
• While the pastry cooks, soften the onions in the oil over a medium heat for 10 mins until golden. Beat the eggs and cream together, then season to taste. Crumble up the hard cheeses and chop or pull the creamy cheese into small pieces. Scatter the cheese into the pastry case, add the onions, then pour in the egg mix. Turn the oven down to 160C/fan 140C/gas 3 and bake for 40 mins until set and lightly golden.

ONION, CHEESE, AND BACON TART

Steps:

• For crust:
• Blend flour and salt in processor. Add butter and shortening; using on/off turns, cut in until mixture resembles coarse meal. Add 2 tablespoons ice water and process until moist clumps form, adding more ice water by teaspoonfuls if dough is dry. Gather dough into ball; flatten into disk. Wrap in plastic and chill at least 1 hour.
• Preheat oven to 400°F. Roll out dough on lightly floured work surface to 11-inch round. Transfer to 9-inch tart pan with removable bottom. Press dough onto bottom and up sides of pan. Pierce crust all over with fork. Freeze 10 minutes. Line crust with foil; fill with dried beans or pie weights. Bake crust 10 minutes. Remove foil and beans. Bake until crust is set and partially cooked through, about 15 minutes longer. Cool crust while making filling. Maintain oven temperature.
• For filling:
• Sauté bacon in medium skillet over medium heat until crisp, about 4 minutes. Transfer bacon to paper towels to drain. Add onion and pinch of sugar to drippings in skillet and sauté until onion is deep golden brown, about 20 minutes. Whisk cream, egg, egg yolk, pepper, salt, and nutmeg in small bowl to blend. Spread onion over bottom of baked crust; sprinkle bacon over, then cheese. Pour cream mixture over.
• Bake until tart is puffed and filling is set, about 25 minutes. Cool tart on rack 10 minutes. Remove pan sides. Serve warm or at room temperature.

SPINACH AND ONION TART

Steps:

• Preheat the oven to 350 degrees. Oil a 10-inch tart pan and line it with the pastry. Keep it in the refrigerator while you prepare the filling.
• Steam the spinach above an inch of boiling water for 2 to 3 minutes, until wilted. You will probably have to do this in batches. I like to use a pasta pot with an insert for steaming spinach, as I can get a lot of it into the insert. Rinse briefly with cold water, squeeze out excess water and chop medium-fine.
• Heat the olive oil over medium heat in a large, heavy skillet and add the onion. Cook, stirring often, until it is tender and beginning to color, about 8 minutes. Add the spinach, thyme and salt and pepper to taste, and stir together. Remove from the heat.
• Whisk the eggs in a large bowl. Add salt to taste (I use about 1/2 teaspoon) and whisk in the milk. Stir in the onion and spinach mixture and the cheeses. Scrape into the pastry-lined tart pan. Place in the oven and bake 40 to 45 minutes, until tart is set and beginning to color on the top. Remove from the heat and allow to cool for at least 15 minutes before cutting. Serve warm or room temperature.

ROASTED BUTTERNUT SQUASH AND CARAMELIZED ONION TART

Steps:

• On a lightly floured surface roll out dough into a 12-inch round (about 1/8 inch thick). Fit dough into an 11-inch tart pan with a removable fluted rim. Freeze shell 15 minutes.
• Preheat oven to 375°F.
• Line shell with foil and fill with pie weights or raw rice. Bake shell in middle of oven until edge is pale golden, about 20 minutes. Carefully remove foil and weights or rice and bake shell 10 minutes more, or until bottom is golden. Leave oven on. Cool shell in pan on a rack.
• Halve squash and scoop out seeds. Lightly brush each cut side with about 1 teaspoon oil and on a baking sheet roast squash, cut sides down, in middle of oven 40 minutes, or until soft.
• While squash is roasting, thinly slice onion and in a heavy skillet cook in 1/2 tablespoon butter and remaining 1 1/2 teaspoons oil over moderate heat, stirring occasionally, until soft and golden brown, about 20 minutes.
• Cool squash and scoop out flesh. In a food processor purée squash. Add whole egg, egg yolk, and cream and blend well. Transfer mixture to a large bowl and stir in cheeses, herbs, onion, salt, and pepper to taste. Pour filling into shell, smoothing top.
• In a small skillet melt remaining tablespoon butter and stir in bread crumbs until combined well. Sprinkle bread crumb mixture evenly over filling. Bake tart in middle of oven 40 minutes, or until filling is set. Cool tart in pan on rack 10 minutes and carefully remove rim.

ALSATIAN ONION TART

Steps:

• Sift the flour into a large bowl then rub in the butter with your (clean) fingers until the mixture resembles fine breadcrumbs.
• Mix the egg yolks with the salt and 3 tablespoons water. Stir into the flour, using a knife, to make a soft and smooth (but not sticky) dough. Add the extra tablespoon of water if the mixture is too dry.
• Pat the dough into a ball, wrap up in cling film and refrigerate for 30 minutes.
• Preheat the oven to 220C/425°F.
• Roll out the pastry on a floured surface and use to line a 10-inch tart pan.
• Prick the pastry all over with a fork and bake blind for 10-12 minutes. Remove from oven and let cool.
• Lower the temperature of the oven to 190C/375F and place a baking sheet in the oven to heat.
• Heat the oil in a non-stick frying pan. Add the onions, bay leaf, thyme, salt and pepper. Cover and cook gently until the onions are soft and transparent, stirring occasionally.
• Add the wine and simmer, uncovered, until all the liquid has evaporated.
• Remove the bay leaf and taste for seasoning.
• Whisk the eggs and cream together.
• Spread the onions into the pastry crust and pour in the egg mixture.
• Place on the hot baking sheet and bake for 15 minutes.
• May be served hot or room temperature.

BRIE, APPLE & ONION TART

Steps:

• Heat oven to 200C/180C fan/gas 6. Unroll the pastry sheet onto a large baking tray (leave it on the paper from the pack). If the edges are not straight, trim them with a sharp knife. Score a border, about 1cm in from the edge. Score a criss-cross pattern over the central piece of pastry (this will prevent it from rising too much) and around the border, if you like. Bake for 15 mins.
• Meanwhile, heat the oil in a large pan. Add the onions and cook for 10-15 mins until softened and starting to caramelise. Stir in the vinegar, bubble for 1 min more, then add the Dijon mustard and thyme, season well and set aside. Slice the apple thinly through the core so a few slices have a nice star in the middle, and remove any seeds. Toss the slices in a splash of vinegar to prevent them from browning.
• The pastry should be puffed and starting to colour. Push down the centre, then spread over the onions. Add blobs of cranberry sauce, then top with the apple slices and brie, overlapping them to cover the tart. Add a few more thyme sprigs, drizzle with a little oil, then put back in the oven for a further 25 mins until the cheese is bubbling and the apple slices are soft. Serve warm or cold.