2 tablespoons olive oil
Preheat oven to 400 degrees F. Heat olive oil in a large nonstick pan and sauté onion, squash, zucchini and garlic until tender; stir in tomatoes. Drain and set aside. Lightly oil or spray the bottom of a 2-1/2 quart casserole or baking dish. Place cooked squash and zucchini mixture in the bottom of the casserole.