Cook the chopped bell pepper until soft (I did this in a skillet).
Whisk the eggs until combined, then add the cooked bell pepper, cheese, sliced serrano pepper and salt and pepper.
Place a spoonful of the pulled pork in each cups of a muffin pan (I used a silicone muffin pan since it's the easiest to get the cups out of when cooked without sticking), dividing evenly. Spoon the egg mixture on top of and around the pork, filling no more than 1/4" from the top of each cup.
Bake the egg muffins in the preheated oven for 20-25 minutes. They will puff up, but as soon as they come back to room temperature, they will deflate.