POTATO CHEESE BOUREKAS

Steps:

• For the potato part of this filling, you can bake a potato, use a leftover baked potato, or use leftover mashed potatoes. If you're baking a potato, place a rack on the lowest part of the oven and another rack in the middle of the oven. Place a baking sheet on the lowest rack of the oven (line with aluminum foil for easier cleanup). Preheat the oven to 400 degrees F. Scrub the potato clean and pat them dry. Stab a few slits on both sides of the potato with a sharp steak knife. (Note that there are two potatoes in these pictures, but you will only need one.)
• Hold the potato over a mixing bowl and rub it with extra virgin olive oil, then coat lightly with kosher salt.
• Place the potato directly on the middle rack above the baking sheet. Let the potato bake for 60-70 minutes till soft inside.
• Squeeze the potato after baking to test for doneness-- it should give when you apply pressure. Remove potato from the oven and let it stand uncovered till cool.
• Peel the potato with your fingers, then mash it. You should end up with about 1 cup of mashed potatoes. Alternatively, you can use a leftover baked potato for this step (of the correct size). You can also use leftover mashed potatoes (make sure they're dairy or pareve if you're keeping kosher). You'll need about a cup of cold or room temperature mashed potatoes total, no matter which of these methods you choose.
• Preheat oven to 350 degrees F. In a mixing bowl, combine mashed potato, feta, kashkaval, egg, a pinch of salt and a pinch of black pepper (if using all feta cheese or pre-seasoned mashed potatoes, no need to add any salt). Use a fork to mix ingredients together till well blended. Make sure to break up any large crumbles of feta with the fork. Reserve mixture.
• On a smooth, clean, lightly floured surface, unfold one of your puff pastry sheets. Use a rolling pin to roll out the sheet to a 12x12 inch square. If using homemade puff pastry, roll your dough out to the same size - a 12"x12" square. Cut the sheet of puff pastry dough into 9 equal-sized squares, each about 4"x4" large.
• Place 1 heaping tablespoon of the potato cheese filling on one corner of each square, spreading it out into a triangle shape 1/4 inch from the edge to halfway across the square. The filling will create a diagonal triangle inside the square.
• Fold the dough square by grasping the opposite corner and folding it up and over the filling to to make a triangle. Pinch firmly along the outer open edge of the triangle to seal.
• You can also crimp the edges with the tines of a fork, if you wish.
• Repeat this process for the remaining squares, then for the second sheet of puff pastry-roll out the pastry, cut into squares, add filling, and seal the triangles.
• Spray your baking sheets with nonstick cooking spray or line with parchment paper. Place 9 bourekas on each sheet, evenly spaced, giving them a little room to expand during baking.
• In a small bowl, whisk together the egg yolk and 2 tsp of cool water. Use a pastry brush to brush a light layer of the egg wash onto the surface of each boureka. Sprinkle the bourekas with sesame or poppy seeds, if desired.
• Bake the bourekas for about 35 minutes, switching the baking sheets between the upper and lower racks halfway through cooking. Bake till golden brown and cooked through.
• Serve warm. Store in a sealed container or plastic zipper bag.
• To freeze bourekas: prepare, fill, and seal the pastries. Do not coat with egg wash or bake. Place the unbaked pastries in a Tupperware or plastic bag in single layers, separating each layer of bourekas with a piece of parchment paper or wax paper to keep them from freezing together. Freeze.
• When ready to bake, take the bourekas out of the freezer (no need to defrost) and arrange them on a baking sheet sprayed with nonstick oil. Coat with thin layer of egg wash and sesame or poppy seeds, if desired. Bake at 350 degrees for 35-45 minutes till golden brown, crisp and flaky.