Bloom Gelatin: Mix powdered gelatin with cold water in a small bowl. Use 1 tablespoon of water for every teaspoon of gelatin. Let it sit for about 10 minutes to bloom.
1 teaspoon gelatin, 1 tablespoon water
Temper Gelatin: Stir 1 to 2 tablespoons of cold heavy cream into the melted gelatin until smooth. If the mixture starts to set too quickly, gently reheat it in a double boiler to keep it liquid.
Whip Cream to Soft Peaks: Whip the heavy cream with powdered sugar and vanilla extract until it doubles in volume and the whisks start leaving a trail behind them.
1 cup heavy cream, 1 teaspoon vanilla extract, 1/4 cup powdered sugar
Add Gelatin Mixture: When the whipped cream has doubled in volume, slowly pour the gelatin mixture into the cream while continuing to whip.
Whip to Stiff Peaks: Whip the cream until it forms firm peaks. If the cream doesn't reach firm peaks due to the added water, aim for slightly softer peaks—they will firm up as the mixture sets. Stop whippeing immediately if it starts to curdle.