Butterbeer: 2 liter cream soda 2 tablespoons Butter extract 2 teaspoons rum extract *drop the extracts into the 2 liter bottle, put on cap and slowly rotate until combined. Cream topping: 1 7oz container of marshmallow creme 1 cup whipping cream 1 teaspoon rum extract *add all items together in an electric mixer and combine until smooth.