Lightly beat eggs and whites. Stir in Parmesan cheese, parsley, seasoning and set aside.
Spray oven-proof skillet. Preheat skillet over medium high heat until drop of water sizzles when added to skillet. Add zucchini, mushrooms, green onion and garlic. Stir fry 2-3 minutes or until zucchini is almost tender. Remove from heat.
Pour egg mixture over vegetables, spread mixture evenly in skillet. Bake uncovered at 350 degrees for 8-10 minutes or until eggs are set. Arrange tomato slices over eggs; sprinkle Mozzarella over frittata. Bake 2 minutes more or until cheese melts. 3 servings.
NOTE: You can transfer to 8-inch round baking dish and increase cooking time to 12-15 minutes.