1 Put the chocolate into a large jug with the coffee.
2 Bring 300 ml of the milk to a boil, then pour over the chocolate and coffee mixture, stirring to melt. Cool slightly.
3 Put the cooled milk into a blender with the ice cream and remaining milk. Blitz until blended, then pour into 4 tall glasses.
4 Whisk the cream until thick and spoon into a piping bag. Pipe a swirl of cream on top of each glass and sprinkle with cinnamon.