In a saucepan, combine the milk, cream, sugar, cinnamon stick, Grand Marnier (if using), and chocolate. Heat over low heat.

Place the egg yolks in a mixing bowl.

Soak 5 sheets of gelatin in a bowl of cold water to soften.

Stir the milk mixture and, as soon as it starts to boil, remove the saucepan from the heat.

Gradually pour the hot milk mixture over the egg yolks, whisking constantly.

Squeeze out the gelatin sheets and mix them into the custard mixture.

Pour into ramekins and refrigerate for at least 2 hours.