Place 4 heaping tablespoons of Fluff and 3 tablespoons of water* in a microwave-safe container, then microwave on high for 15 seconds. Remove and stir until smooth.
* For a fancier topping, replace water with creme de menthe, Kahlua, or other liqueur of your taste.
Use more or less Fluff to reach the desired thickness. Refrigerate after use. Microwave 20 seconds after refrigeration and stir.