Preheat the oven to 350 degrees. Line a mini muffin pan with liners.

Melt the butter and then combine the butter, powdered sugar, and graham cracker crumbs. Mix well.

Place 1 tablespoon of the mixture into each cup and bake for 5 minutes. Remove from the oven and use the end of a wooden spoon to make a cup in the middle of each muffin cup.

Place one chocolate rectangle inside of each cup. Top with half a marshmallow. Bake for 2 minutes.

Remove from oven and immediately place another chocolate rectangle on top of the marshmallow. Allow to cool for 2-3 minutes then gently swirl the chocolate piece around on top of the marshmallow.

Cool for 15 minutes then remove from pan and enjoy!