Wild Mushroom Lasagna

From Gourmet Magazine.

• Ready In: 1 hr 45 mins
• Serves: 12

Ingredients

• For the mushroom Filling

• 3  cups water
• 2  ounces dried porcini mushrooms
• 2  lbs fresh white mushrooms
• 2  large zucchini
• 1  large onion
• 3  garlic cloves
• 5  tablespoons unsalted butter
• 6  tablespoons sherry wine
• 2  teaspoons  chopped fresh thyme leaves
• 2 1⁄2 teaspoons salt
• 1⁄4 teaspoon fresh ground black pepper

• For the Sauce

• 1⁄2 cup unsalted butter
• 1⁄2 cup all-purpose flour
• 5  cups  whole milk
• 4 1⁄2 ounces  freshly grated parmesan cheese
• 2  teaspoons Dijon mustard
• 1 1⁄2 teaspoons salt
• 18  sheets  dry no-boil  lasagna noodles
• 1⁄2 lb  freshlly grated mozzarella cheese
• 1 1⁄2 ounces  freshly grated parmesan cheese

Directions

1. Make the filling: In a small saucepan bring water to a boil and remove pan from heat. Stir in the porcini. Soak the porcini 20 minutes. Lift out the porcini, squeezing out excess liquid, and reserve soaking liquid. In a sieve, rinse the porcini to remove any grit and pat dry. Chop the porcini and transfer to a large bowl. Simmer reserved soaking liquid until reduced about 1/4 cup. Pour the liquid through a sieve lined with dampened paper towels into the bowl with the porcini.
2. Quarter white mushrooms and in a food processor pulse 3 batches until finely chopped. Cut zucchini into 1/4-inch dice. Chop onion and mince garlic. In a 12-inch heavy skillet heat 1 tablespoon butter over moderate heat until foam subsides and cook 1/3 white mushrooms with 2 tablespoons sherry, stirring, until liquid mushrooms give off is evaporated and they begin to brown. Add mushroom mixture to the porcini. Cook remaining mushrooms in 2 batches in butter with remaining sherry in the same manner and add to the porcini mixture. In skillet cook onion in remaining tablesppon butter, stirring, until softened. Stir in garlic, thyme, salt, and pepper and cook, stirring, until fragrant, about 30 seconds. Stir onion inot mushroom mixture until combined. Filling may be made one day ahead and chilled, covered.
3. Make the sauce: In a 3 quart heavy saucepan melt butter over moderately low heat and whisk in flour. Coo roux, whisking 3 minutes and whisk in milk. Bring sauce to a boil, whisking constantly and simmer, whisking occasionally, 3 minutes. Stir in Parmesan (4 1/2 ounces), mustard, and salt. Remove pan from heat and cover surface of sauce with waxed paper. Sauce may be made one day ahead and chilled, covered. Bring sauce to room temperature before proceeding,.
4. Preheat oven to 375 degrees and butter a 3 quart baking dish (9x13 inch).
5. Assemble the Lasagna: Spread 1 1/4 cups sauce in baking dish and cover with 3 pasta sheets, making sure they don't touch each other. Spread 1/3 filling over pasta sheets in the dish and top with 3 more pasta sheets, gently pressing down layers to remove air pockets. Top pasta sheets with 1/3 mozzarella. Continue layering in the same manner with sauce, pasta sheets, filling and mozzarella, ending with mozzarella (dish will be filled to the rim). Spread remaining sauce over top and sprinkle with Parmesan (1 1/2 ounces). On a foil lined baking sheeting, bake lasagna in middle of oven until bubbling and golden, about 45 minutes. Let lasagna stand 20 minutes. Lasagna my be made one day ahead and chilled, covered. Bring lasgana to room temperature and reheat before serving.