Break the chocolate into small chunks and tip into a bowl with the coffee and alcohol. Bring 250ml of the cream to the boil, then pour over the chocolate mixture and stir until the chocolate has melted and the mixture is smooth. Divide the mix between 6 coffee cups and leave to set overnight in the fridge.
To serve, whip the remaining cream with the sugar until just set. Spoon the cream onto the chocolate pots and serve dusted with cocoa powder so each cup looks like a cappuccino.