1. Sprinkle gelatin over cold water in medium bowl; let stand for 5 minutes to soften.
2. In medium saucepan, combine skim milk, sugar replacement and salt. Heat to boiling point over medium heat. Pour boiling liquid over gelatin mixture; stir to dissolve gelatin completely. Add vanilla extract. Chill for at least 1 1/2 hours or until almost set.
3. Using electric mixer at high speed, beat blancmange until very frothy. Spoon into four 10-ounce custard cups.