Prep the basket: Line your air fryer basket with a small piece of parchment or foil to catch drips. Leave space around the edges for airflow.
Build the base: Place graham cracker squares in a single layer in the basket. Top each square with one marshmallow, standing upright.
Toast the marshmallows: Air fry at 370°F (188°C) for 2–3 minutes until the tops are golden and puffed. Watch closely—marshmallows go from perfect to scorched fast.
Add chocolate: Carefully open the basket, place a square of chocolate on each hot marshmallow, and top with another graham cracker square. Press gently to help the heat melt the chocolate.
Brief melt (optional): Return to the air fryer for 10–20 seconds if you want the chocolate extra melty. Don’t overdo it or the crackers can soften.
Cool slightly and serve: Let them sit for 30–60 seconds so the chocolate settles. Eat warm and gooey.