In a blender, combine 1 1/4 cup milk, 1/4 cup hot fudge sauce, 4 whole marshmallows, 4 whole graham crackers, and 2 shots espresso (if using). Blend on a low speed for 10 to 15 seconds until mixed.
Add 4 cups ice cubes and blend until smooth, about 60 seconds.
(Optional) Serve topped with additional marshmallows, whipped cream, or a dollop of marshmallow cream and use a kitchen torch to toast it for extra ridiculous goodness.
Video
[yeetvid]
Notes
Coffee Options: 1 to 2 shots espresso, 1 teaspoon instant espresso powder, or 1/4 to 1/2 cup brewed coffee.