In a shallow bowl, combine the breadcrumbs, grated Parmesan cheese, garlic powder, oregano, salt, and black pepper. Mix well.
In another bowl, beat the egg.
Dip each chicken breast into the beaten egg, ensuring it’s fully coated, then transfer it to the breadcrumb mixture, pressing down firmly to coat both sides evenly.
Once coated, place the chicken breasts in the air fryer basket in a single layer (you may need to cook in batches).
Air fry the chicken at 400°F (200°C) for 10 minutes.
After 10 minutes, carefully flip the chicken breasts over and air fry for an additional 5 minutes until they are golden brown and cooked through (internal temperature should reach 165°F).
Remove the chicken from the air fryer and spoon marinara sauce over each piece, followed by a generous sprinkle of shredded mozzarella cheese.
Return the chicken to the air fryer and cook for an additional 2–3 minutes, or until the cheese is melted and bubbly.
Carefully remove the chicken and let it rest for a couple of minutes. Garnish with fresh basil leaves if desired.