Mix milk, egg, water, vanilla and pancake mix together in a bowl. Make sure batter is thick. If needed, add more pancake mix to thicken.
Assemble the sandwich like this: bread, 2 slices of cheese, 5 slices of ham, 2 slices of cheese and bread.
Using toothpicks, stab the corners of the sandwich to lock both slices of bread together.
Dip the sandwich in the batter on both sides and place sandwich in parchment-lined air fryer basket.
Cook on 370 for seven minutes, flip and cook for three more minutes.
Remove and serve with powdered sugar dusting and dip in some jelly.
Storage: This sandwich is best when served fresh and warm. I recommend only making what you plan to eat. Don't make extra sandwiches as they can become soggy once they cool down. I've heard of people freezing them and then reheating in the air fryer or toaster oven but the bread gets too soft for me. Substitutions: Drizzle with honey instead of dusting with powdered sugar if you would like. Choose to use Gruyere or Gouda cheeses. Change out the meat to be turkey instead of ham. Air Fryer Paper: Remember to line the air fryer with paper or use parchment paper that you punched holes into so air can continue to flow and clean up is easy. If you don't use paper, the mess is going to outweigh the enjoyment of the sandwich. Toothpicks: Don't skip this step or the sandwich will be hard to flip and stay together.