How to Make It
Heat oven to 450°F. Cut mushroom caps into quarters. Combine mushrooms, bell peppers, fennel, zucchini, onion, tomatoes, and garlic in a large bowl. Add olive oil and 1/2 teaspoon each of the salt and pepper; toss well to coat. Arrange vegetable mixture in a single layer on a rimmed baking sheet. Bake in preheated oven until well browned but not crispy, about 45 minutes, stirring after 30 minutes. Cool 10 minutes on baking sheet. Reduce oven temperature to 350°F.
Stir together cooked pasta, ricotta, provolone, egg, egg yolk, basil, oregano, cayenne, 1 cup of the mozzarella, 1/2 cup of the Parmesan, and remaining 1 teaspoon salt and 1/4 teaspoon pepper in a large bowl.
Spread 1 cup of the marinara in the bottom of a 13- x 9-inch baking dish coated with cooking spray. Layer one-half of pasta mixture in dish; top evenly with vegetable mixture. Spread 1 cup of the marinara over vegetables; top with remaining half of pasta mixture. Spread remaining marinara evenly over top, and sprinkle with remaining mozzarella and Parmesan cheeses. Bake at 350°F until bubbly and golden brown, 35 to 40 minutes.