Spinach Frittata

Set oven to broil.Beat egg whites vigorously until very frothy. Whip in egg yolk and milk. Add garlic and green onions.Set aside.
Preheat olive oil in an ovenproof nonstick skillet. Add white onion and saute on medium heat until soft. Add spinach. When spinach has wilted, pour egg mixture over top, stirring and shaking just enough to make sure eggs reach bottom of pan. Lower heat. Sprinkle cheese over top.
Cook slowly on low heat until frittata is firm at the edges and the center is beginning to set.
Place under broiler until lightly browned on top. You can serve the frittata either in the pan or on a platter. It will drop in height as it cools. Add mushrooms or red pepper as desired.