Set oven broiler to low. Return cupcakes to the oven about 6" below the broiler. Keep a close eye in the marshmallows. They will burn quick, so you don't want them in there more than a minute. Remove from oven. Use a knife to cut a small slit in each marshmallow. Using the knife blade as an edge and to help you keep the hole open, insert the Hershey's chocolate piece. Top with graham cracker crumble.