Mushroom-and-Spinach Lasagna

Name: Mushroom-and-Spinach Lasagna
Ingredients: 9 uncooked or 12 oven-ready lasagna noodles; 4 tablespoons unsalted or salted butter; 4 tablespoons unsalted or salted butter; 1 pound shiitake and oyster mushrooms; 1 pound shiitake and oyster mushrooms; 1 onion, chopped; 2 large garlic cloves, finely chopped; ½ teaspoon dried Italian seasoning; ½ teaspoon fine sea salt; ½ teaspoon coarsely ground black pepper; ¼ cup all-purpose flour; 3 tablespoons sherry or white wine; 3 tablespoons sherry or white wine; 2½ cups half-and-half; ¼ teaspoon ground nutmeg; 5 ounces baby spinach; 1 cup (4 ounces) shredded mozzarella cheese, divided; ½ cup (2 ounces) freshly shredded Parmesan cheese, divided; 1 cup ricotta cheese