1 envelope Knox unflavored gelatine
1/4 cup cold water
2 cups (1 pint) whipped or heavy cream
1/2 cup powdered sugar
Chill large mixing bowl at least 15 minutes. Meanwhile, in small saucepan, sprinkle unflavored gelatine over cold water; let stand 1 minute. Stir over low heat until gelatine is completely dissolved, about 2 minutes. In chilled bowl, while beating cream on low speed, gradually add gelatine mixture, then beat on medium speed until thickened, about 5 minutes. Add sugar, then speed until soft peaks form, about 2 minutes.
If you plan to pipe the cream, whip cream until soft peaks form.
For a flavored whipped cream, simply add your favorite extracts or liqueurs, to taste, with gelatine mixture, then proceed as above.