Preheat oven to 400 degrees. Lightly grease 6 - 8oz ramekins. Sprinkle zucchini, tomato, onion and cheese evenly between the ramekins. Stir together the remaining ingredients until well blended. Pour over the vegetables and cheese in each ramekin.
Bake uncovered 35 minutes or until the center is set. Cool 5 minutes.