Bloom the gelatin: Sprinkle gelatin over cold water in a small bowl. Let it sit for 5-10 minutes until spongy.

Heat the cream mixture: In a saucepan, combine heavy cream, milk, and sugar. Split the vanilla bean and scrape seeds into the mixture (or add vanilla extract). Heat over medium heat until steaming but not boiling.

Dissolve gelatin: Remove the cream mixture from heat. Add the bloomed gelatin and stir until fully dissolved.

Strain and pour: Strain the mixture through a fine sieve into a jug to remove any lumps. Pour into ramekins or glasses.

Chill: Refrigerate for at least 4 hours, preferably overnight, until set.

Make berry coulis: Blend berries and powdered sugar until smooth. Strain to remove seeds. Drizzle over panna cotta before serving.

Serve: Run a knife around the edges of the ramekins, dip briefly in warm water, and invert onto plates. Or serve directly in glasses with coulis.