Preheat the oven to 400˚ F. Place the butter in a 10" cast iron skillet. Melt the butter in the oven. Remove the skillet from the oven.
Place the chocolate into the skillet. Drizzle the cream over the top. Bake for 6-8 minutes or until the marshmallows are golden brown.
Remove the skillet from the oven and serve hot with the graham crackers for dipping. *be careful around the hot skillet