Pound chicken breasts to ¾-inch even thickness using meat mallet.
Pat chicken dry and season both sides with salt and pepper.
Set up three bowls: flour in first, whisked eggs and water in second, panko-Parmesan mixture in third.
Dredge chicken in flour, dip in egg, then press into panko mixture coating completely.
Preheat air fryer to 380°F for 3-5 minutes.
Spray air fryer basket with cooking spray. Place breaded chicken in single layer.
Spray tops of chicken with cooking spray. Air fry 6 minutes.
Flip chicken, spray other side. Air fry 4-5 minutes until internal temperature reaches 165°F.
Top each breast with 3 tablespoons marinara and ¼ cup mozzarella.
Air fry 2-3 minutes until cheese melts and bubbles.
Let rest 2-3 minutes before serving. Garnish with fresh basil.