Preheat a non-stick skillet coated with cooking spray. Add onion and saute 2 minutes until crisp-tender. Add sausage and saute another 3 minutes. Remove from heat and cool at least 5 minutes.
3
Combine remaining ingredients in a large bowl; stir with a whisk. Add sausage mixture and blend well.
4
Coat mini muffin tin with cooking spray and divide egg mixture among 9 muffin cups.