In a small bowl, sprinkle the gelatin over the cold water and let it sit for about 5 minutes until it blooms.
In a saucepan over medium heat, combine the heavy whipping cream, whole milk, and granulated sugar. Stir until the sugar is dissolved and the mixture is warm but not boiling.
Remove the saucepan from heat and stir in the bloomed gelatin until fully dissolved. Add the vanilla extract and mix well.
Allow the mixture to cool slightly, then pour it into serving cups or a large bowl.
Refrigerate for at least 4 hours or until the Bavarian cream is set.
Once set, top with fresh mixed berries and garnish with mint leaves if desired.