Prep the leeks: Slice the leek lengthwise, rinse between the layers to remove grit, then thinly slice. Pat dry.

Cook the bacon: In a skillet over medium heat, cook diced bacon until crisp, about 5–7 minutes. Transfer to a paper towel–lined plate. Spoon off all but 1 teaspoon of the rendered fat.

Sauté the leeks: In the same skillet, cook the leeks over medium heat in the remaining bacon fat for 3–4 minutes until softened and lightly sweet. Season with a pinch of salt and pepper. Let cool slightly.

Whisk the eggs: In a bowl, whisk eggs, milk, garlic powder, onion powder, and a pinch of salt and pepper until smooth. Stir in bacon, leeks, cheese, and herbs.

Prepare the cups: Lightly grease silicone muffin cups or tray with nonstick spray. Place them in the air fryer basket. Preheat your air fryer to 325°F (165°C) for 2–3 minutes if your model benefits from preheating.

Fill the cups: Divide the mixture evenly, filling each cup about 3/4 full. Don’t overfill—frittatas puff slightly as they cook.

Air fry: Cook at 325°F (165°C) for 9–12 minutes, depending on cup size and your air fryer. They’re done when the centers are just set and a toothpick comes out with moist crumbs, not wet batter.

Rest and release: Let the frittatas rest in the cups for 3–5 minutes. This helps them finish setting and release cleanly. Gently pop them out.

Serve: Enjoy warm or at room temperature. Add a sprinkle of herbs or a dollop of sour cream if you like.