MUSHROOM-POLENTA LASAGNA

Steps:

• Make the sauce: Soak the dried porcini in 3 cups hot water, 30 minutes. Drain, reserving 2 cups of the soaking liquid. Roughly chop the porcini.
• Heat 1 tablespoon each butter and olive oil in a large pot or Dutch oven over medium-high heat. Add half of the button and shiitake mushrooms and cook, undisturbed, until slightly browned on the bottom, about 2 minutes. Continue to cook, stirring, until soft, 2 to 3 more minutes; transfer to a bowl. Repeat with another 1 tablespoon each butter and olive oil and the remaining button and shiitake mushrooms. Transfer to the bowl and add 1/2 teaspoon salt.
• Reduce the heat to medium and add the remaining 1 tablespoon each butter and olive oil to the skillet. Add the onion and porcini and cook, stirring, until the onion is soft, about 4 minutes. Stir in the garlic and red pepper flakes. Add the tomato paste and cook, stirring, until darkened, 1 to 2 minutes. Add the reserved 2 cups porcini liquid, the crushed tomatoes, button and shiitake mushrooms and 1/2 teaspoon salt. Bring to a simmer and cook, stirring occasionally, until thickened, about 30 minutes. Remove from the heat and stir in the parsley; season with salt.
• Prepare the lasagna: Bring 7 cups water to a boil in a large saucepan; transfer to a large heatproof bowl. Meanwhile, bring 3 cups water to a boil in a separate large saucepan. Gradually whisk the polenta and 1 1/2 teaspoons salt into the bowl of hot water. Cover the bowl tightly with foil and set over the saucepan of boiling water. Reduce the heat so the water is simmering; cook the polenta until the liquid is absorbed, about 15 minutes. Remove from the heat, uncover and vigorously whisk in the parmesan, eggs and nutmeg.
• Preheat the oven to 350 degrees F. Lightly brush a 3-quart baking dish with olive oil. Spread one-third of the polenta in the dish and top with half of the mushroom sauce. Sprinkle with 1 cup mozzarella. Repeat the layers (polenta, sauce, mozzarella), then top with the remaining polenta. (If the polenta gets too thick, whisk in a little hot water.)
• Loosely cover the dish with foil and bake until bubbly, 50 minutes to 1 hour. Turn on the broiler. Uncover the lasagna and top with the remaining 1 cup mozzarella; broil until melted, 2 to 3 minutes. Sprinkle with parsley. Let stand 15 minutes before serving.