In a medium saucepan, combine the heavy cream and sugar. Place the saucepan over medium heat and stir until the sugar is completely dissolved. Remove the saucepan from the heat and stir in the vanilla extract.
In a small bowl, sprinkle the gelatin over the cold water and let it sit for a few minutes until the gelatin softens.
Add the softened gelatin to the warm cream mixture and stir until the gelatin is completely dissolved.
Divide the mixture among four dessert cups or ramekins.
Let the panna cotta cool to room temperature, then cover with plastic wrap and refrigerate for at least 4 hours, or until set.
Serve the panna cotta in the dessert cups, topped with fresh berries or your choice of topping.