Chop chocolate into rough chunks. Place in a bowl with softened butter.
Combine cream, cardamom and coffee beans in a small saucepan and bring to a boil. Set aside to rest for 30 minutes.
Filter coffee liquid through a fine sieve. Pour over butter-chocolate mixture, set in a double boiler over boiling water. Stir until the chocolate melts and the mixture is smooth. Add the liqueur and stir.
Place in the fridge overnight. Roll into small round chocolate truffles.
Roll truffles in cocoa powder or finely chopped nuts (eg. hazelnuts, almonds etc..)