On-the-go egg breakfast

Our girls are giving us an abundance of eggs right now. When we have extras we either make quiche or these egg cups. We make these using the following:

Ingredients:
1 diced onion
1 diced red bell pepper
1 cup diced baby portobello mushrooms
These are sauteed until tender.
We fill the muffin cups 1/3-1/2 with the sauteed vegetable mix. Then we whisk 8-12 eggs adding salt and pepper to taste. We pour the whisked eggs into the cups until the cups are almost filled.
Bacon, cheese, or whatever else one would desire can be used instead.
Bake at 350 for 15-20 minutes.
These freeze well and can be reheated and taken in the car to be eaten.