Poke each potato 2 inches deep with a knife three times. Microwave the potatoes for 5 minutes. Flip the potatoes over and microwave for an additional 5 minutes, or until they are soft.
Using an oven mitten to protect your hand from the hot potato, slice them in half lengthwise and scoop out the flesh, leaving a 1/4 inch of potato on the edges.
In a small bowl, mash the potatoes and add the sour cream, milk, Parmesan, White Cheddar and garlic salt. Fill the potato skins with the mashed potato mixture and using the back of a spoon, form a divot in the center. Fill each divot with 3 Tablespoons of diced ham.
Arrange 4 potato skins in a small Airfryer or 8 in an XL Airfryer. (If using a regular smaller Airfryer, you will have to do these in 2 batches, or if you are a small family like myself, refrigerate the other half for another meal before baking!)
Bake at 300° in the Airfryer for 8 minutes. Top with shredded cheddar and bake an additional 2 minutes.
Serve topped with diced green onions.