Lightly grease a baking dish with cooking spray. Set aside.
In a bowl, add the cream of mushroom soup, milk, salt and black pepper and mix well.
Add in the ham, potatoes and onion and mix well.
Add 1 cup of cheese and stir to combine.
Place the mixture into the prepared baking dish evenly.
Slide the Air Fryer Basket inside and adjust the temperature to 400 °F to preheat for 5 minutes.
After preheating, arrange the baking dish into the Air Fryer Basket.
Slide the basket into Air Fryer and set the time for 25-28 minutes.
While cooking, stir the ham mixture twice.
After 25 minutes of cooking, top the casserole with the remaining cheese.