Pour 1/2 cup milk into a small saucepan; bring to a simmer over medium heat. Place cornstarch in a small bowl; gradually add water, stirring with a wire whisk until blended. Add to simmering milk; bring to a boil, stirring constantly. Cook 1 minute, stirring constantly. Combine cornstarch mixture, remaining 1 cup milk, and vanilla in a large bowl; freeze mixture 1 hour or until a 1/8-inch-thick layer of ice forms on the surface. Beat mixture at high speed of an electric mixer 5 minutes; gradually add sifted powdered sugar, beating until soft peaks form. Cover and chill. Combine coffee, whiskey, and sugar; stir well. Yield: 8 servings (about 83 calories per 3/4 cup coffee and 1/2 cup topping). Per serving: 99 Calories; 0g Fat (1% calories from fat); 3g Protein; 13g Carbohydrate; 2mg Cholesterol; 53mg Sodium Serving Ideas : Pour into mugs; spoon topping onto coffee. NOTES : Cover and store remaining topping in refrigerator. Recipe by: Cooking Light, Nov/Dec 1992, page 77 Posted to MC-Recipe Digest V1 #397 by igor@digex.net on Jan 28, 1997.