Yield: 6-8 servings.
6 tablespoons salted butter
4 tablespoons all-purpose flour
3 cups milk
1 (16-ounce) can pumpkin
1 cup shredded Parmesan cheese, plus extra for garnish
2 teaspoons salt
½ teaspoon freshly grated nutmeg
½ pound fresh mushrooms, sliced
2 cloves garlic, minced
1 shallot, minced
2 cups ricotta cheese
1 box no-boil lasagna noodles
Preheat oven to 350º. Prepare a 9×12-inch baking dish by evenly coating with olive oil or butter. Set aside. In a medium saucepan, heat 5 tablespoons of butter over medium-low heat until melted. Add the flour and stir until smooth. Over medium heat, cook until the mixture turns a light golden, sandy color, about 6 to 7 minutes.
Meanwhile, heat the milk in a separate pan until just about to boil. Add the hot milk to the butter mixture 1 cup at a time, whisking continuously until very smooth. Add pumpkin. Bring to a boil. Add ½ cup Parmesan cheese. Cook 10 minutes, stirring constantly, then remove from heat. Season with salt and nutmeg, and set aside until ready to use.
In a saucepan, heat remaining tablespoon of butter until melted. Add mushrooms, garlic, and shallot. Cook on medium heat 10 minutes.
In a separate mixing bowl, blend ricotta and remaining ½ cup Parmesan.
Ladle 1 cup of sauce into baking dish. Place one layer of lasagna noodles on top of sauce. Spread half of the cheese mixture on top of the noodles. Add a second layer of noodles. Layer with mushroom mixture. Top with 1 cup sauce. Add next layer of noodles, followed by remaining cheese mixture. Pour remaining sauce over the top, and cover dish with aluminum foil. Bake for 1 hour at 350º. Remove from oven and let sit (covered) 15 minutes before serving. Garnish with extra Parmesan.