In a small, heavy-bottomed saucepan, heat the chocolate, milk, sugar and cinnamon stick, stirring constantly, until the chocolate has melted and the mixture is smooth. Bring to the boil while beating with the whisk. Remove from heat and stir in coffee (and brandy). Take out the cinnamon stick. Place the orange peel in 2 pre-warmed glasses, add the hot mixture and serve.
It is also nice to put a piece of the cinnamon stick in melted chocolate, then let it set and stir the drink with it.