Turn oven on broil and let it heat up for two minutes. Line a baking sheet with parchment paper. Place 17 marshmallows on parchment side by side. Broil the marshmallows until the tops are just lightly toasted. This takes about 30 seconds to 1 minute so watch them carefully. I usually just leave the oven door open so I can watch them closely. If you toast them for too long they'll be mushy and too melty to get off of the parchment - it's not the biggest deal in the world.

Once marshmallows are toasted, scoop ice cream into blender, pour in the milk and add the toasted marshmallows. Blend everything until completely smooth. Drizzle inside of cup with chocolate sauce (optional) then pour in milkshake. Top with an extra flattened toasted marshmallow and drizzle with more chocolate sauce (also optional). Sprinkle top with graham cracker crumbs and serve