How to Make It
In a large skillet, warm oil over medium heat. Add peppers, squash, zucchini, eggplant, onion and mushrooms and cook, stirring, until vegetables are crisp-tender, 12 to 14 minutes. Add garlic and sauté 2 minutes longer. Transfer to a bowl, stir in herbs and season with salt and pepper.
In a bowl, combine 1 1/2 cups mozzarella, ricotta, 1/4 cup Parmesan, spinach and egg; mix well. Preheat oven to 350ºF. Line a large baking sheet with foil and mist a 9-by-13-inch baking dish with cooking spray.
Spread 1 cup sauce over bottom of baking dish. Place 4 noodles over sauce; do not allow noodles to overlap (break up noodles if necessary). Spread 1 cup sauce over noodles. Spread 1/2 ricotta mixture on top. Using a slotted spoon, spread 1/2 vegetable mixture on top. Repeat layers, ending with noodles. Spread remaining marinara on top of noodles; sprinkle with remaining mozzarella and Parmesan.
Lightly mist a large piece of foil with cooking spray and carefully cover dish with foil. Place dish on baking sheet and bake for 45 minutes. Remove foil and bake until cheese has melted and filling is bubbling, about 15 minutes longer. Remove lasagna from oven and let stand for at least 10 minutes before serving.