1Heat oven to 400°F. Lightly spray 9x5-inch (1 1/2-quart) glass loaf dish with cooking spray. Sprinkle zucchini, tomato, onion and cheese in dish.
2In medium bowl, stir remaining ingredients with fork or whisk until blended. Pour over vegetables and cheese.
3Bake 30 to 35 minutes or until knife inserted in center comes out clean. Let stand 5 minutes before serving.