Combine sugar, water, Sweet N Low, egg whites, and cream of tartar in top of a double boiler and beat at high speed for 1 minute. Set over simmering water in the bottom of the double boiler. Continue to beat at high speed for 4-5 minutes or until soft peaks form.

Remove from heat. Add vanilla to frosting and continue beating at high speed 1-2 minutes or until thick enough to spread on a cooled cake. Use about 2 1/2 tablespoons per portion if frosting individually; or use this amount to frost a 2-layer cake or a 9 inch square cake, both of which would then be cut into 16 equal servings. You can change the frosting easily by adding a couple drops of food coloring and some flavoring, such as 2 drops of red coloring and some peppermint flavoring. 1 serving = 1 vegetable (1-1 1/2 tablespoons may be used as a topping for cake or pudding without counting it as an exchange. Calories = 23