Gelatin is commonly associated with jiggly fruit desserts, but this ingredient will also thicken cake frosting. This powerful thickener is especially useful in whipped cream frosting recipes that do not use icing sugar for thickening. Gelatin stabilises the whipped cream and keeps it from deflating after beating. Look for powdered gelatin in the baking goods aisle with the flavoured fruit gelatin desserts. Be sure to use unflavored gelatin to avoid changing the taste of your frosting.
Place the metal bowl in the freezer to chill it, which makes whipping the cream easier.
Sprinkle the gelatin over the water in a small saucepan and let it sit for 5 minutes to soften.
Gently heat the gelatin over medium-low heat, without boiling, for 2 minutes. Remove the gelatin from the heat and allow it to cool to room temperature.
Remove the bowl from the freezer and add the whipping cream and vanilla.
Beat the cream on medium speed for 1 minute or until the cream thickens. When you pull out the whisk attachment, the peaks formed in the cream should have drooping tips.
Mix the icing sugar gently into the cream, until it is completely incorporated.
Drizzle the cooled gelatin mixture into the cream while the mixer is still beating the cream at medium speed.
Beat the frosting until the peaks formed when you remove the mixer's whisk from the cream are firm and stiffly hold their shape. Use the frosting to cover the cake.