Preheat the oven to 350ºF. Butter a 12-cup muffin pan and set aside.
In a medium cast-iron skillet over medium-high heat, cook the bacon until crispy. Transfer to paper towels to drain.
In a large bowl, whisk together the eggs, cream cheese, mayonnaise, salt, and pepper until smooth.
Pour the batter into 10 to 12 muffin cups to about ¾ full. Sprinkle the tops evenly with the bacon and about 1/2 tablespoon of the diced bell pepper. Evenly sprinkle
with the green onion and about 1/2 tablespoon of the cheese. Lightly stir each bite with a toothpick.
Bake for about 30 minutes, or until the eggs are set and cooked through. Remove from the pan and let cool slightly before serving.
Tip: These remove easier if baked in a silicone muffin pan.