In a saucepan, combine the chopped rhubarb, granulated sugar, and water. Cook over medium heat until the rhubarb is soft and the mixture is syrupy, about 10-15 minutes.

In a mixing bowl, whisk the heavy cream, powdered sugar, and vanilla extract until soft peaks form.

Allow the rhubarb mixture to cool slightly, then fold it gently into the whipped cream until combined. Spoon the mixture into serving glasses and chill before serving.