Sprinkle gelatin over cold water in a small bowl; bloom five minutes.

Heat cream, milk, and sugar in a saucepan over medium heat until sugar dissolves and mixture is hot, not boiling.

Remove from heat; stir in vanilla and bloomed gelatin until completely dissolved.

Divide evenly among four ramekins or glasses; refrigerate at least three hours, until set.

Once firm, top each with a layer of mango puree; chill one more hour before serving.