Put the chocolate in a bowl set over barely simmering water and stir until melted.
Bring the sour cream or crème fraîche to the boil over a medium heat with the granulated sugar, then stir this into the chocolate until smooth. Finally, stir in the Calvados or brandy.
Chill this mixture for about 30 minutes until you can take spoonfuls and work them between the fingers into small cylinders. Roll in grated chocolate and chill until required.
© 1998 Alastair Little and Richard Whittington estate. All rights reserved.