Hydrate the gelatin by mixing the gelatin powder with cold water in a small bowl and letting it sit for about 5 minutes.
In a medium saucepan, combine heavy cream, whole milk, and granulated sugar. Warm over medium heat, stirring gently until the sugar dissolves completely.
Remove the saucepan from heat and incorporate the bloomed gelatin, stirring until it dissolves. Mix in the vanilla extract and mango puree until well blended.
Pour the creamy mango mixture into serving glasses or ramekins and refrigerate for a minimum of 4 hours to set.
For the vanilla topping, whip heavy cream with powdered sugar and vanilla extract until soft peaks form.
Once the panna cotta has set, spoon the vanilla topping over each serving.
Chill before serving and enjoy!