Break the graham crackers in half and place 9 halves in the air fryer, or as many as can fit leaving a little bit of space between each one for the air to circulate.
Cut the marshmallows in half and place the cut sides down on the graham cracker squares. Cutting them helps the marshmallows cook more evenly and prevents them from blowing off the cracker while frying.
Air fry at 370°F for 4 minutes, then remove from the air fryer and immediately add the peanut butter cups and top with the unused half of the graham crackers, pressing together. Enjoy immediately.
Notes
I use a Cosori 5.8qt, different sized air fryers may be able to hold more or less.
If you want really gooey s’mores, you can air fry for 3 minutes, then add the chocolate and air fry for 1 minute more. However, you do risk a messier air fryer and it makes it more difficult to remove them from the air fryer.
I used regular-sized marshmallows, but you could also use jumbo.
If you’re making multiple batches, don’t cut the marshmallows in half until you’re ready to put them on the graham crackers otherwise they will lose their stickiness and may not stay on the crackers while cooking.
For classic s'mores, you can use 3 Hershey bars broken into thirds and a third on each graham cracker. I also like using the caramel Ghirardelli squares.