Line an angular flat casserole dish (approx. 18 x 32 cm) with cling film. Coarsely chop 300 g each of the dark and milk chocolate coating, melt together in a hot water bath, cool down a little. Heat up espresso powder and cream (do not boil!). Melt butter and white fat in pieces while stirring. Cool down lukewarm. Stir in the melted chocolate coating well. Pour into the mould. Cool down. Cover and chill for about 12 hours.
Turn over and cut into cubes of about 2 cm. Line plate or tray with baking paper. Quickly form cubes into balls with cool hands. Put them on the plate. Chill for at least 1 hour
Chop the rest of the chocolate coating and melt in a hot water bath. Dip the balls on a fork into the chocolate, let them drip off. Leave to dry. Dust with icing sugar. Store in a cool place