Preheat the oven to 350° F.
Throw the graham crackers in a plastic bag and crush by rolling with a rolling pin.
Melt the butter and mix in with the graham crackers.
Line a baking sheet with parchment paper and lay out the graham cracker mix.
Sprinkle 1 cup of marshmallows over the top, and bake for 7 - 10 minutes until the marshmallows are slightly browned.
While the base is in the oven, melt the chocolate.
Pull the base out of the oven, then spread the melted chocolate over the top. Reserve a small amount of chocolate to sprinkle on top.
Sprinkle the remaining 1/2 cup of marshmallows over the top and then drizzle the remaining chocolate over the top.
Freeze the bars for 1 hour to harden.
After an hour, break up the base into pieces to enjoy.
Store any leftovers in an airtight container.