In a microwave-safe dish, sprinkle gelatin over cold water. Whisk until absorbed and let sit for 5 minutes.

In a large chilled bowl, beat together cold heavy cream, powdered sugar, and vanilla extract until thickened.

Check the gelatin. If solidified, microwave briefly until liquid but not hot, about 5-10 seconds. Stir to smooth.

With the mixer on low, drizzle in the gelatin, then gradually increase speed to medium/high and beat to stiff peaks.

Use the frosting immediately to pipe or spread on cakes or cupcakes (or anywhere else you fancy!).