Prepare the air fryer and molds: Preheat your air fryer to 350°F (175°C). While it warms up, lightly grease 4 silicone or metal muffin cups with cooking spray or a touch of olive oil. This prevents sticking and ensures your egg cups release easily after cooking.

Mix the egg base: In a medium bowl, crack the eggs and add the milk. Whisk thoroughly until the yolks and whites are fully combined and the mixture is slightly frothy. This will make your egg cups fluffy and tender.

Add fillings: Stir in the chopped spinach, shredded cheese, and minced garlic (if using). Season with a pinch of salt and black pepper. Make sure the ingredients are evenly distributed so each egg cup gets a little bit of everything in every bite.

Fill the molds: Pour the egg mixture into the prepared muffin cups, filling them about 3/4 full to allow room for the eggs to rise while cooking. Avoid overfilling, or the mixture may spill over during air frying.

Air fry the egg cups: Carefully place the muffin cups in the air fryer basket, making sure they are upright and not touching. Cook at 350°F (175°C) for 10–12 minutes, checking around 10 minutes. The egg cups should be set but still slightly soft in the center for a moist texture.

Cool slightly and serve: Remove the egg cups from the air fryer and let them cool for 1–2 minutes before gently removing them from the molds. Serve warm for breakfast or brunch. You can pair them with avocado slices, a light salad, or even a slice of whole-grain toast for a complete meal.