Sprinkle the gelatin over cold water in a small bowl and let it bloom.

Combine the bloomed gelatin, sugar, and vanilla extract in a saucepan.

Gently heat the mixture over low heat until the gelatin fully dissolves, stirring constantly.

Remove from heat and let cool for about 10 minutes.

Whip the egg whites with cream of tartar in a clean bowl until stiff peaks form.

Fold the cooled gelatin mixture into the whipped egg whites gently.

Fold in the whipped heavy cream until fully incorporated.

Pour the mixture into a serving dish or individual cups, smoothing the top.

Refrigerate for at least 2 hours, or until fully set.