Preheat your oven to 350°F (175°C). Grease a muffin tin with cooking spray or butter.
In a mixing bowl, whisk together the eggs and milk until well combined.
Stir in the shredded cheese, diced bell peppers, chopped spinach, and cooked bacon or ham.
Season with salt and pepper to taste.
Pour the mixture evenly into the greased muffin tin, filling each cup about 3/4 full.
Bake for 18-20 minutes or until the egg bites are set and slightly golden on top.
Let them cool for a few minutes before removing from the tin. Serve warm or store for later.