Heat oven to 450°F. Coat large nonstick skillet with cooking spray; heat over medium heat until hot.
Pour in eggs. As eggs begin to set, gently pull the eggs across the pan with an inverted turner, forming large soft curds. Continue cooking -- pulling, lifting and folding eggs – until thickened and no visible liquid egg remains. Do not stir constantly. Remove from heat.
Spread pizza sauce evenly on muffin halves; place on baking sheet. Top with eggs and cheese, dividing evenly.
Bake in 450°F oven until cheese is melted, about 5 minutes. Sprinkle with oregano.
Pizzas can be baked in toaster oven at 450°F until cheese is melted, 1 to 2 minutes.