Cheese is one of those secret ingredients that improve all recipes, especially when melted. But this does not mean that it is a good idea to fill the surface with cheese, especially if it contains a lot of water like mozzarella. Besides making a mess in your air fryer, the water can ruin the texture of the dish you wanted to gratin. Instead, consider using cheese in smaller quantities or as a topping after the main cooking has been done. This way, you can still enjoy the delicious, melted goodness without compromising the performance of your air fryer.