Carefully butterfly the chicken by cutting in half widthwise all the way through to create 4 thin pieces of chicken; season both sides with salt and black pepper.
Place flour in a shallow bowl; season with a large pinch of salt and a few grinds of black pepper.
In another shallow bowl, beat eggs to blend.
In a third shallow bowl, combine panko, Parmesan, oregano, red pepper flakes, and garlic powder.
Working one at a time, coat the chicken in flour, shaking off any excess.
Dip into eggs, letting excess drip off, then finally dip into the panko mixture, gently pressing to adhere and ensuring both sides of the chicken are well-coated.
Working in batches if necessary, in an air fryer basket, arrange chicken in a single layer.
Cook at 400°F, turning once, for 5 minutes per side.
Top the chicken with marinara and mozzarella.
Continue to cook at 400°F until the cheese is melted and golden, about 3 minutes more.
Divide the chicken among plates.
Garnish with parsley.
