Preheat oven to 375°F.
Grease 6 muffin tin wells, then line the walls of each well with a strip of bacon.
Then cut one piece of bacon into thirds and use what you need to line the bottom as well. I usually put one full-width slice on the bottom, plus one I've cut in half . . . Continue the process until you run out of bacon. You should have 4 to 6 cups total.
Bake in the preheated oven for 10 minutes.
While the bacon is baking, whisk together the eggs in a small bowl and prepare the filling ingredients.
After 10 minutes, remove muffin pan from oven and distribute the eggs evenly between cups.
Add in filling ingredients. You want the cups to be about 80% full. In this batch I added cheese, tomatoes, spinach, garlic, mushrooms and fresh thyme.
Place pan in the oven and bake for 25-30 minutes, or until the eggs are set.
After you've removed the bacon egg cups from the oven, use a butter knife to gently separate the bacon shell from the muffin tin.
Lift the bacon egg cups out, season with salt and pepper, garnish with herbs if desired, and serve.