Chop the chocolate and place it in a bowl. Bring the cream to the boil with coffee beans or grounds, then pour it through a fine-mesh sieve over the chocolate.
Add the rum and stir until the mixture is completely smooth and all the chocolate has melted.
Pour the chocolate into a square tin and chill for a couple of hours.
Remove the chocolate truffle mixture from the fridge and leave it to stand for 10 minutes. Then turn the mixture out onto a chopping board, cut it into irregular, uneven squares and roll them in cocoa powder.
If the coffee truffles are not eaten straight away, they should be stored in the fridge or at a maximum of 15 degrees. Enjoy!
