Heat the cream in a small saucepan over medium heat just until it begins to simmer. Remove the pan from the heat and add the chocolate, the vanilla pod (cut in half to fit if necessary), and the vanilla seeds. Let steep for at least 10 minutes.

Remove the vanilla bean (set it aside for another use or discard it), and whisk the cream mixture to blend it well. In a small heat-proof mixing bowl, whisk the sugar and egg yolks together until the yolks are pale yellow and frothy.

Slowly whisk the cream mixture into the egg yolks. Whisk continuously until combined. Strain the mixture through a fine-mesh sieve into another bowl. Divide the mixture equally among six ½-cup ramekins.

Place a kitchen towel or a rack in the bottom of a 6-quart slow cooker, and add the hot water. Gently place the ramekins in the slow cooker. If necessary, add more hot water so that it reaches halfway up the sides of the ramekins.

Cook on high for 1½ hours. Carefully remove the pots de crème from the slow cooker and transfer them to a baking sheet. Place them in the refrigerator to cool. Once cooled, the pots de crème can be covered with plastic wrap and stored in the refrigerator for up to 24 hours. Allow the pots de crème to come almost to room temperature before serving.