For the coffee cream, break the couverture into pieces and heat it with the cream in a water bath at a low temperature. When the chocolate has melted, add the coffee powder, stir until it has dissolved and stir in the mascarpone. Let the cream cool, cover with cling film and put in the refrigerator for about 8 hours, preferably overnight.
Proceed in the same way for the chocolate cream, only the coffee powder is omitted.
Before serving, stir the creams thoroughly and use a skin sack to squirt them in layers into tall glasses. Garnish with brittle.