In a saucepan, combine the heavy cream, whole milk, sugar, and vanilla bean seeds. Heat the mixture over medium heat, stirring occasionally, until it comes to a gentle simmer. Remove from heat.

In a small bowl, sprinkle the powdered gelatin over the cold water. Let it sit for about 5 minutes to bloom.

After the gelatin has bloomed, whisk it into the warm cream mixture until completely dissolved.

Strain the mixture through a fine-mesh sieve to remove any lumps or vanilla bean particles.

Divide the mixture evenly among your serving glasses or ramekins. Cover each with plastic wrap and refrigerate for at least 4 hours, or until set.

Once set, you can serve the panna cotta directly in the glasses or ramekins, or unmold them onto serving plates. To unmold, run a knife around the edge of each panna cotta and dip the bottom of the container in hot water for a few seconds to loosen it.

Serve chilled, optionally garnished with fresh berries, fruit coulis, or a drizzle of caramel sauce.