Preheat oven to 375 degrees Fahrenheit. Grease 12 muffin tins very well.

Place some onion and pepper on the bottom of each muffin tin. Sprinkle some cheese on top of the vegetables.

In a bowl, beat eggs with a fork. Add baking powder, salt, and milk. Pour into muffin cups, filling them almost full. Bake in preheated oven for 20 minutes or until set.