Ingredients

　　3 1/2 cups milk

　　1/2 of a vanilla bean, split lengthwise

　　6 ounces fine-quality white chocolate, chopped fine, plus shaved white chocolate for garnish

　　1/3 cup Cognac or Armagnac, or to taste

　　3 tablespoons dark or white crème de cacao, or to taste

　　Whipped cream for garnish

　　In a large heavy saucepan, combine the milk, the vanilla bean halves, and a pinch of salt and bring the mixture just to a boil over moderate heat. Remove the pan from the heat and let the mixture stand, covered, for 15 minutes. Scrape the seeds form the vanilla bean back into the mixture, discarding the pods, and reheat the mixture until it just comes to a boil. In a small heatproof bowl, combine the chopped chocolate with about 2/3 cup of the hot milk mixture and whisk the mixture until the chocolate is melted and the mixture is smooth. Whisk the chocolate mixture into the remaining milk mixture and simmer the hot chocolate, whisking, for 2 minutes. Stir in the Cognac and the crème de cacao. (For a frothy result, in a blender blend the hot chocolate in batches.) Divide the hot chocolate among mugs and top it with the whipped cream and the shaved chocolate.