Truffes de Chambéry or chocolate truffles

Ingredients

Makes about 25 truffles
- 300 g dark chocolate
- 150 g butter
- 50 g icing sugar
- 2 egg yolks

Preparation

Grate the dark chocolate and mix it with the softened butter and the sugar. 
Add the egg yolks, beating the mixture well to produce a smooth but stiff cream. A few drops of coffee essence can also be added to give more flavour. Leave to stand over night in a cool place.
Divide the mixture into small balls and roll them in the remaining grated chocolate.