Prepare pasta according to package directions. While pasta is cooking, warm the vegetable oil in a large saucepan over medium-low heat. Add the onion, zucchini and garlic. Cover the pan and cook until the vegetables are very soft, about 10 minutes. Season with salt and pepper.
Preheat oven to 325?F. Blend together the egg whites and Ricotta cheese until smooth. In a 3-quart casserole dish, layer the pasta, Ricotta cheese and tomato mixture, ending with a layer of the tomato mixture. Sprinkle the top with grated Mozzarella and Parmesan cheese. Bake until golden brown on top and bubbling, about 45 minutes.
|