Whipped cream makes a light and creamy filling or topping for almost any dessert, but regular whipping cream becomes watery after just a few hours. Although whipped cream will never be as firm or as long-lasting as royal frosting, buttercream or pastry cream, you can stabilize whipped cream with gelatin. The gelatin is essentially a protein, which binds the whipped cream so it becomes firmer and lasts longer.
Pour unflavored gelatin in a glass or plastic bowl. Unflavored gelatin comes in small packets. One or two packets will suffice, depending on how thick you want the whipping cream and how much cream you're using.
Pour a few tablespoons of ice cold water over the gelatin. Allow it to set without stirring for five minutes. The gelatin will soften, expand and absorb the water, creating a firm putty.
Add a few tablespoons of boiling water or cook the gelatin in the microwave for 20 seconds to soften and liquify it. Stir it until smooth.
Heat a few tablespoons of whipping cream in the microwave until hot. Stir the hot cream into the gelatin mixture. This extra step ensures that the gelatin remains smooth, not grainy, when you add it to the whipping cream.
Pour cold whipping cream into a cold bowl. Use a balloon whisk or mixer to whip the cream until it forms soft peaks. Stir in the powdered sugar and any flavorings.
Add the gelatin mixture slowly and whip it in completely. Frost the cake immediately. After about 30 minutes, the whipped cream will be firm and ready to spread or pipe.