Preheat the oven to 350°F. Grease a muffin tin with cooking spray or olive oil.
In a large mixing bowl, whisk together the eggs and milk until well combined.
Stir in the shredded cheddar cheese, diced bell peppers, diced onion, chopped spinach, salt, black pepper, garlic powder, and paprika. Mix until all ingredients are evenly distributed.
Pour the egg mixture evenly into the prepared muffin tin, filling each cup about 3/4 full.
Bake in the preheated oven for 18-20 minutes, or until the egg bites are set and lightly golden on top.
Remove from the oven and let cool for a few minutes before carefully removing the egg bites from the muffin tin. Serve warm or allow to cool completely before storing.