Line a 9x13 with parchment paper. Place 6 graham crackers on the bottom, plus 1 ½ broken into 3 pieces to fill the gap. (see video)
Line a baking sheet with parchment paper and toss the marshmallows on it. Broil for 1-2 minutes, watching carefully until they are nicely toasted. Don't take your eyes off of them for a minutes, because they can burn super quickly. Remove from the oven and set aside.
Scoop the vanilla ice cream over the graham crackers, and gently spread it until it reaches all the end of the crackers.
Drizzle chocolate sauce over the ice cream.
Spoon the toasted marshmallows over the ice cream and chocolate sauce.
Place 7 ½ graham crackers over the ice cream, the same way you did the ones on the bottom.
Freeze for at least 4 hours before cutting into squares. Enjoy!