From: Readers Digests "Great Recipes for Good Health" Calories: 5 cal. per tbsp. Uploaded by: Donna Ransdell, COOKING echo 1. Put the skim milk in a small metal bowl, set in freezer, and let stand just til ice crystals begin to form (about 15 minutes). 2. Remove from the freezer and add the dry milk powder and cream of tartar. With hand electric mixer, whip the mixture at high til foamy. 3. Beat in 1 tsp. lemon juice and continue beating til the mixture begins to thicken. Beat in another tsp of lemon juice and if desired, the sugar, and continue beating til the mixture peaks softly. Add the remaining 2 tsp lemon juice and continue whipping to stiff peaks. Fold in vanilla (if desired), and serve immediately as a dessert topping or however you use Cool Whip.