Cut the chicken breasts in half to make two thinner whole pieces.
Place a large piece of plastic wrap over a chopping board and place one of the pieces of chicken in the middle. Pull over the plastic wrap over the top of the chicken to cover it.
Use a mallet or rolling pin to pound the chicken out so that it's thin and even.
Season both sides with salt and pepper and lay it back on the plastic wrap.
Mix together the mustard and mayo and spread some of it over one side of teh flattened chicken. Top with a slice of ham and cheese.
Roll up the chicken breast into a pinwheel and use the clingfilm to wrap it and secure tightly. Repeat with the other bit of chicken.
Refrigerate for at least 30 minutes.
Add the flour to one bowl, beat an egg in another and add the panko and parmesan to a third.
Take the chicken out of the fridge and unwrap. If it doesn't hold together you can secure it with a toothpick, but remember to remove before serving!
Dredge each piece of chicken in the flour, then egg, then breadcrumbs, coating well all over on each layer. Set to one side.
Preheat the air fryer to 350F.
Once hot, spray the basket with oil and place in the pieces of chicken. Spray the tops again with oil.
Set to cook at 350F for 18 minutes. Halfway through cooking, spray again with oil to make it extra brown and crispy.