Preheat oven to 350 degrees F.
In a medium bowl, combine eggs and egg whites with milk. Whisk and set aside.
Slice red bell pepper into strips. Toss in 1/2 Tbsp olive oil and place on greased baking sheet. Dust with garlic powder, salt, and pepper to taste. Broil until pepper is slightly browned on edge, 3-5 minutes.
Cut shallot into medium sized slices. Add 2 Tbsp olive oil to pan. When hot, add shallots and spinach. Salt and pepper to taste. When spinach has reduced and shallots are tender, reduce heat to low.
Remove peppers from oven and slice into smaller pieces. Add to shallot mixture.
Grease muffin pan (very well) and spoon in shallot and pepper mix into each cup. Pour in the eggs until cups are almost full. Add Parmesan and green onion on top for garnish. Bake for 20 minutes.
Remove from the oven and serve immediately with avocado slices.