To a medium saucepan, placed over low heat, pour in all of the ingredients. Heat until a very gentle simmer and whisk until the chocolate has melted and is cohesive. Remove the cinnamon stick and vanilla bean and discard.
Divide amongst mugs and garnish with whipped cream, marshmallows or chocolate shavings.
Notes
Tips and Tricks
Milk Chocolate - If you want to use milk chocolate (say that's all you have), feel free to eliminate the sugar in the recipe.
Stir regularly - Stir it regularly to avoid a skin from forming on the top.