Roughly break the chocolate, place in a saucepan with cocoa, vanilla sugar, cinnamon and sugar. Heat over low heat until the chocolate is dissolved. Add milk, heat while stirring, but do not boil.
Remove from the fire, stir together the egg yolks and sugar until frothy. Beat into the milk mixture together with the brandy. Immediately pour into cups and serve with long cinnamon sticks (to stir).