In a medium bowl, whisk the eggs, milk, salt, and pepper until fully combined and smooth. Gently fold in the chopped spinach and shredded cheese until evenly distributed.
Pour the egg mixture into silicone muffin cups or a silicone mold, filling each about ¾ full to allow for rising. If adding extras like bell peppers or bacon, sprinkle them in now.
Place the filled cups into the air fryer basket, ensuring they have space for air circulation. Set the air fryer to 300°F (150°C) and cook for 10-12 minutes, or until the egg bites are set and lightly golden on top.
Allow the egg bites to cool for 2-3 minutes before gently removing them from the molds. Serve warm with a side of fresh fruit, a dollop of salsa, or a sprinkle of herbs.
