Heat a large Dutch oven over medium-high heat. Coat pan with cooking spray. Add bell peppers, onion, zucchini, and mushrooms; sauté 10 minutes or until vegetables are crisp-tender and mushroom liquid evaporates. Add garlic; sauté 30 seconds.
Combine 1 1/2 cups mozzarella, ricotta, 1/4 cup Parmesan, and egg, stirring well.
Spread 1 cup Basic Marinara over bottom of a 13 x 9-inch baking dish coated with cooking spray; top with 3 noodles. Spoon 1 cup Basic Marinara evenly over noodles. Top evenly with one-third of ricotta mixture and one-third of vegetable mixture. Repeat layers twice, ending with noodles. Top with remaining 1 cup Basic Marinara. Sprinkle evenly with remaining 1/2 cup mozzarella and remaining 1/4 cup Parmesan. Cover and bake at 350° for 45 minutes. Uncover and bake an additional 10 minutes or until cheese melts. Let stand 10 minutes.