Begin by peeling and slicing your potatoes into thin, even slices. Chop the onion finely and dice the cooked ham into bite-sized pieces.

In a large mixing bowl, combine the cream of mushroom soup with milk to create a creamy mixture. Season this with kosher salt and black pepper to taste.

Start by spreading a thin layer of the soup mixture at the bottom of the air fryer basket or a compatible air fryer-safe dish. Then, add a layer of potato slices, followed by a layer of chopped onion and diced ham.

Sprinkle a layer of shredded cheddar cheese over the ham. Repeat these layers until all ingredients are used up, finishing with a final layer of cheese on top.

Preheat your air fryer to 360°F (180°C). Once preheated, place the air fryer-safe dish or basket in the air fryer.

Cook for about 20-25 minutes. The cooking time might vary depending on your air fryer model and the thickness of the potato slices. Halfway through the cooking time, you might want to check the casserole and gently stir or rearrange the layers for even cooking, though this step is optional.

The casserole is done when the potatoes are tender and the cheese is melted and slightly golden on top. You can check the tenderness of the potatoes with a fork.

Once cooked, let the casserole sit for a few minutes to cool down slightly. This rest period allows the layers to set, making it easier to serve.

Optionally, garnish with fresh herbs like parsley or chives before serving. Serve warm and enjoy your hearty and delicious Air Fryer Ham and Potato Casserole!