
Whisk eggs, milk, salt, and pepper together in a bowl until well combined.
Grease a 6-inch round baking pan or oven-safe dish with cooking spray or butter.
Scatter bell pepper, onion, and spinach evenly across the bottom of the pan.
Pour the egg mixture over the vegetables and top with cheddar and feta cheese.
Air fry at 320°F for 15-18 minutes until the center is set and the top is lightly golden.
Let rest for 2 minutes before slicing into wedges and serving.
Tip: Use a lower temperature to cook the frittata gently — too high and the edges will overcook while the center stays runny. A 6-inch pan fits most air fryer baskets perfectly.
Share your result and inspire others
Liked this recipe? There's more.
Get new recipes straight to your inbox.

Crispy bacon cups cradling a set egg with melted cheddar. 10-minute breakfast.

Silky custard-like egg bites with gruyère and everything bagel seasoning. Meal prep hero.

Thick-cut brioche dipped in vanilla cinnamon custard, air fried golden and crispy outside, custardy inside.