Preheat the broiler on High. Line a cookie sheet with aluminum foil. NOTE: Do not use parchment paper under the broiler, it may catch on fire.
Lay out graham crackers, followed by chocolate, then marshmallows.
Put the tray under the broiler for approximately 40 seconds or until browned to your liking. NOTE: Keep an eye on these! They turn in a second and the timing will depend on how close your oven rack is to the top. Remove from oven and add any other toppings you wish to include, and a graham cracker top, and smush into gooey perfection.