Prepare the gelatin: In a small bowl, sprinkle the 7g (2 tsp) of unflavored gelatin powder over 30ml (2 tbsp) of cold water. Stir briefly to combine, then let it sit for at least 5-10 minutes to bloom and soften. The gelatin will absorb the water and become jelly-like.

Infuse the cream: In a medium saucepan, combine 500ml (2 cups) of heavy cream and 75g (1/3 cup + 1 tbsp) of granulated sugar. If using a vanilla bean, split it lengthwise with a sharp knife, scrape out the tiny seeds with the back of the knife, and add both the seeds and the pod to the cream mixture. If using vanilla extract, you will add it later.

Heat the cream mixture: Place the saucepan over medium-low heat. Stir gently and continuously until the sugar is completely dissolved and the cream is hot but not boiling. You should see steam rising from the surface and small bubbles forming around the edges. This usually takes about 5-8 minutes.

Remove from heat and steep: Once the cream is hot and the sugar is dissolved, remove the saucepan from the heat. Cover the saucepan and let the mixture steep for about 15-20 minutes. This allows the vanilla flavor from the bean (if used) to fully infuse into the cream.

Strain and add gelatin: After steeping, remove the vanilla bean pod from the cream mixture. If you used vanilla extract instead of a bean, add 1 teaspoon of vanilla extract now. Gently reheat the cream mixture if it has cooled significantly, ensuring it is warm enough to dissolve the gelatin. Add the bloomed gelatin mixture to the warm cream, whisking continuously until the gelatin is completely dissolved and no lumps remain. This should take about 1-2 minutes.

Strain the mixture (optional but recommended): For an extra smooth panna cotta, pour the mixture through a fine-mesh sieve into a clean bowl or a large measuring cup with a spout. This removes any tiny bits of vanilla bean seeds that may have separated or any undissolved gelatin.

Portion the panna cotta: Lightly grease 6 ramekins or small serving glasses (approximately 120-150ml or 4-5 oz capacity) with a neutral oil or cooking spray. Pour the panna cotta mixture evenly into the prepared ramekins. Aim for about 120-130ml (around 1/2 cup) per ramekin.

Chill the panna cotta: Carefully place the filled ramekins on a tray. Cover each ramekin loosely with plastic wrap to prevent a skin from forming. Refrigerate for at least 4-6 hours, or preferably overnight, until the panna cotta is fully set and firm to the touch. It should jiggle slightly but hold its shape.

Prepare the berry coulis: While the panna cotta is chilling, prepare the berry coulis. In a small saucepan, combine 200g (1.5 cups) of mixed berries (fresh or frozen) with 15g (2 tbsp) of powdered sugar (optional) and 5ml (1 tsp) of lemon juice (optional).

Cook the coulis: Place the saucepan over medium heat. Cook, stirring occasionally, until the berries have broken down and the mixture has slightly thickened, about 5-8 minutes. If using frozen berries, this may take a little longer. The mixture should be saucy but not watery.

Strain the coulis (optional): For a smoother coulis, press the cooked berry mixture through a fine-mesh sieve into a clean bowl, discarding the seeds and solids. This will result in a silky smooth sauce.

Chill the coulis: Let the berry coulis cool completely. Once cooled, cover and refrigerate until ready to serve. The coulis will thicken slightly as it chills.

Serve the panna cotta: To serve, you can either serve the panna cotta directly in the ramekins or glasses. Alternatively, to unmold, run a thin knife around the edge of each ramekin, then invert it onto a serving plate. Give it a gentle shake to release. Spoon a generous amount of the chilled berry coulis over or around the panna cotta.