In a small bowl, sprinkle the gelatin powder over the cold water. Let it sit for 5-10 minutes to bloom (soften and absorb the water).

In a medium saucepan, heat the whole milk with the vanilla bean and scraped seeds over medium heat until it just begins to simmer. Remove from heat and let steep for 10 minutes to infuse the vanilla flavor. If using vanilla extract, add it later.

In a heatproof bowl, whisk the egg yolks and 1/2 cup granulated sugar until light in color and creamy.

Remove the vanilla bean from the milk. Slowly temper the hot milk into the egg yolk mixture, whisking constantly to prevent curdling. Pour the tempered mixture back into the saucepan.

Cook over medium-low heat, stirring constantly with a wooden spoon or spatula, until the custard thickens enough to coat the back of the spoon (about 5-7 minutes). Do not boil. If using a thermometer, it should reach 170-175°F (77-79°C).

Remove from heat. Add the bloomed gelatin to the hot custard and stir until completely dissolved. If using vanilla extract, stir it in now.

Strain the custard through a fine-mesh sieve into a clean bowl to ensure a smooth texture. Set the bowl over an ice bath and stir occasionally until the custard is cool to the touch but still liquid (not set). This helps it cool quickly and evenly.

In a separate, very cold bowl (preferably chilled beforehand), whip the 1 1/2 cups of cold heavy cream until soft peaks form. Be careful not to over-whip.

Gently fold the whipped cream into the cooled custard in two additions until just combined. Be careful not to deflate the cream.

Lightly grease your individual molds or ring mold with a neutral oil or non-stick spray (this helps with unmolding). Pour the Bavarian cream mixture into the prepared molds.

Refrigerate for at least 4 hours, or preferably overnight, until thoroughly set.

While the Bavarian cream chills, prepare the berry coulis. In a small saucepan, combine the 2 cups mixed berries, 2-4 tbsp granulated sugar (adjust to your sweetness preference), and 1 tsp lemon juice.

Cook over medium-low heat, stirring occasionally, until the berries break down and the sauce thickens slightly (about 8-10 minutes).

For a smoother coulis, pass it through a fine-mesh sieve to remove seeds and pulp. Let it cool completely. Store in the refrigerator until ready to serve.

To unmold the Bavarian cream, briefly dip the bottom of each mold into warm water (about 10-15 seconds) or run a thin knife around the edge. Invert onto serving plates.

Serve the Bavarian cream with a generous drizzle of berry coulis, fresh mixed berries, and a sprig of fresh mint.