Cream butter, spices and sugars. Blend with softened ice cream; mix well. Pack into covered container and store in freezer. To serve, put generous spoonful into mug. Add 2 oz. rum and mix well. Add boiling water to fill. Adjust ice cream mixture to taste. Serve at once. Drink slowly. (This was just a little too sweet for my taste. The next time I made it, I toned down the sugar to 1 cup of the powdered sugar and more ice cream.) Makes 25 servings.