1. Preheat oven to 350F.
2. Mix egg and ricotta cheese. Add chopped vegetables, onions and mushrooms. Season with salt and pepper.
3. Spread half cup of Alfredo sauce on bottom of 9x9-inch baking dish lightly sprayed with vegetable oil.
4. Top with 2 noodles, one-third of the vegetable mixture, two more noodles and half cup of sauce.
5. Repeat layers, finishing with 2 noodles and remaining sauce.
6. Cover with foil and bake for 30 minutes. Remove foil and sprinkle with mozzarella cheese. Bake an additional 20 minutes.