Pat chicken dry and pound to an even thickness.
Season both sides with salt, pepper, garlic powder, and Italian seasoning.
Set up breading station: flour in one bowl, whipped eggs and milk in another, panko breadcrumbs mixed with Parmesan in a third.
Dredge each chicken piece in flour, shaking off excess.
Dip into egg mixture, then coat thoroughly with breadcrumb mixture, pressing gently to adhere.
Preheat air fryer to 375 °F (190 °C).
Lightly spray chicken with cooking spray and air fry for 10–12 minutes, flipping halfway, until golden and cooked through.
Top each chicken piece with marinara sauce, mozzarella, and Parmesan cheese.
Return to air fryer and cook 3–4 minutes until cheese melts and bubbles.
Garnish with fresh herbs if desired and serve hot over pasta or with a side salad.