Spritz both sides of each eggplant slice with nonstick spray and place on a baking sheet. Bake in the oven until browned and softened, about 20 minutes, carefully flipping halfway through.
Meanwhile, in a bowl, combine egg white(s), ricotta cheese, basil, garlic, salt, and nutmeg. Stir well and set aside.
Bring a skillet sprayed with nonstick spray to medium-high heat on the stove. Add mushrooms and, stirring occasionally, cook until softened, about 4 minutes. Stir mushrooms into ricotta mixture and set aside.
In a small bowl, combine Italian seasoning with crushed tomatoes. If you like, season with black pepper and additional salt, to taste. Mix well and set aside.
Spray a large loaf pan with nonstick spray. Pour 1/4 cup tomatoes evenly into the bottom of the pan. Top with 1 lasagna sheet. Spread half of the ricotta-mushroom mixture on top, followed by another 1/4 cup tomatoes. Top with 1 eggplant slice.
Repeat layering with 1/4 cup tomatoes, 1 lasagna sheet, the remaining ricotta-mushroom mixture, the remaining 1/4 cup tomatoes, and the remaining eggplant slice.
Evenly top with mozzarella and grated topping. Bake until the cheese starts to brown, 20 to 25 minutes. Serve and enjoy!