Preheat oven to 375. In a large bowl, scramble all of the eggs (4) with the milk (1 cup). Season with salt (1 Tsp), pepper (½ Tsp), basil (½ Tsp), and garlic powder (½ Tsp).
Stir in the melted butter (2 tbsp) once it'S cooled. (Too hot and it will begin to cook the eggs!).
Add in the bisquick and whisk together well.
Grease or use nonstick spray to prepare your pie dish. Add in the chopped onion, zucchini, parmesan (¼ cup), mozzarella (1 cup), and cheddar (½ cup). Use your hands to toss it around a bit so everything is well distributed.
Carefully pour the egg batter into the pie dish, covering all of the vegetables. Go around the edges to ensure that all the crevices get filled.
Cover with aluminum foil to prevent the top from burning. For wide and shallow quiche dishes bake for 25-30 minutes. For deep and smaller pie dishes, bake for 40-45 minutes.