Preheat the air fryer to 200°C (400°F).
Slice each chicken breast lengthwise to make 2 thin fillets, yielding about 8 cutlets total.
Place two sheets of plastic wrap on a cutting board and put two fillets between them; pound with a meat mallet or rolling pin until each is about 1/4 inch thick. Repeat with remaining fillets.
Set up a dredging station: flour in the first shallow bowl, beaten eggs in the second, and combine panko, grated Parmesan, and Italian seasoning in the third.
Season both sides of each fillet with salt and pepper. Working quickly, dredge each fillet in flour and shake off excess, dip into the beaten eggs, then press into the panko-Parmesan mixture to fully coat.
Arrange a single layer of breaded cutlets in the air fryer basket (do not overcrowd). Lightly spray the tops with cooking spray.
Air fry for 8 minutes, then carefully flip the cutlets, spray the other side lightly with cooking spray, and cook for an additional 6–8 minutes until golden and the internal temperature reaches 165°F (74°C).
Remove the cutlets from the air fryer and serve immediately with lemon if desired.