Bring the cream to the boil, remove from the stove. Break the chocolate into pieces and melt in it while stirring. Cool down at room temperature for about 2 hours
Cream butter and icing sugar. Stir in chocolate cream by the spoonful. Fill into 1 plastic bag, cut off a small corner. Pour into the balls just under the edge. Cool overnight
Coarsely chop the chocolate coating and melt in a hot water bath. Dip balls into it with a fork. Let them drip off on a grid for about 5 minutes. Roll in chocolate shavings. Cool for about 1 hour. Dust with cocoa. Store in a cool place