In a large skillet, fry the bacon until crispy.
Remove the bacon and drain the grease, reserving some of the bacon grease.
Spray a muffin pan with cooking spray. Place the bacon on the sides of each muffin, to act as the “cup”.
In a bowl, mix together the eggs, reserved bacon grease, parmesan cheese, and chives.
Pour the mixture into the muffin “cups”.
Bake in an oven preheated to 350 degrees for about 12-13 minutes, until eggs are firm.
Remove the cupcakes from the muffin pan with a rubber spatula and place a slice of tomato and avocado on each one.