Note: This recipe comes from Le Marche in central Italy, where wild mushrooms, including porcini, are plentiful. From "Mediterranean Cookbook," edited by Marie-Pierre Moine.
• 9 oz. wild or cultivated mushrooms or 1 3/4 oz. dried porcini, soaked and drained
• 4 tbsp. unsalted butter, divided
• 2 tbsp. flour
• 2 c. whole milk
• 4 tbsp. diced prosciutto
• Salt and freshly ground black pepper
• 9 oz. dried lasagna noodles
• 2 tbsp. olive oil, plus extra for greasing
• 4 tbsp. mascarpone or heavy cream
• 4 tbsp. grated Parmesan or pecorino cheese
• 1 egg, beaten
Clean the mushrooms and wipe over the caps — do not rinse. Depending on the size, slice or dice them. In a heavy-bottomed saucepan, melt half the butter, add the mushrooms, and cook until they lose most of their moisture. Remove and set aside.
In the same pan, melt the remaining butter, then stir in the flour and cook gently until the mixture looks sandy, but do not let it darken. Gradually whisk in the milk until you have a smooth sauce — it's easier if you heat the milk first. Boil and stir for 10 minutes, until thick enough to coat the back of a wooden spoon. Add salt and pepper to taste. Remove a ladleful of the sauce and reserve. Stir the mushrooms and prosciutto into the remaining sauce.
Meanwhile, cook the lasagna in plenty of boiling salted water for 6 to 7 minutes, until it begins to soften but is still al dente. Pour the pasta into a colander, pass briefly under cold running water to stop it from cooking further, and drain. Separate out the pasta, leaving them a little moist.
Preheat the oven to 350 degrees. Lightly oil the bottom of a medium-sized gratin dish (or 8-inch square pan) and line with about one-third of the pasta. Spread with half the mushroom sauce and top with another layer of pasta. Repeat the layering. Whisk the reserved sauce with mascarpone, cheese and egg. Top the pasta with the sauce and sprinkle the reserved cheese and a trickle of oil. Bake for 10 to 15 minutes.