Preheat the air fryer. Set it to 300–320°F (150–160°C). Preheating helps the muffins rise and set evenly. If your air fryer runs hot, stick to 300°F.

Prep your cups. Lightly grease silicone muffin cups with cooking spray or a thin brush of oil. Place them in the air fryer basket in a single layer with a little space between each for airflow.

Cook or warm the add-ins. If using raw vegetables like mushrooms or onion, sauté them briefly to remove excess moisture. Pat cooked meats dry to avoid greasy muffins. This step prevents soggy bottoms.

Whisk the eggs. In a large bowl, whisk together eggs, milk, salt, pepper, and optional garlic and onion powder until the mixture is smooth and lightly frothy. Don’t overbeat; just combine well.

Assemble the cups. Divide vegetables and meats evenly among the cups (about 1–2 tablespoons per cup). Sprinkle a little cheese into each—save some for the top.

Pour in the egg mixture. Fill each cup about 3/4 full. Leave room for rise. Top with the remaining cheese and a pinch of herbs if using.

Air fry. Cook for 10–13 minutes at 300–320°F. Start checking at 10 minutes. The muffins should be set in the center and lightly puffed. A toothpick inserted should come out with just a hint of moisture, not wet egg.

Rest before removing. Let the muffins sit in the air fryer for 2–3 minutes with the basket pulled out. They’ll finish setting and deflate slightly, which makes them easier to remove.

Serve or cool. Enjoy warm, or let them cool on a rack before storing. Garnish with extra herbs or hot sauce if you like.