Place chocolate bars in the freezer, and chill well. Once the bars are very chilled mash them with a rolling pin, coffee mug, and then unwrap them. Place broken candy bars back into freezer. Butter a 9 by 13 inch baking pan. Melt five cups of marshmallows and butter in a large saucepan over low heat. Stir occasionally.
Once the marshmallows have melted remove pot from the stove. Add in cereal and mix well. Add in your remaining 1 cup of marshmallows and chocolate bar pieces. Smash mixture into the buttered baking pan, and place pan in the refrigerator. Once these have cooled serve.