Place the broken-up chocolate in a pan.
Add the diced butter and allow to melt over a very low heat for 2 to 4 mins.
Off the heat, stir the chocolate and butter and add the egg yolks then the icing sugar. Mix again.
Allow to cool, then add 8 crumbled Gavottes before the mixture solidifies.
Refrigerate for at least 1 hour.

Crumble the remaining Gavottes onto a plate.
Make the dough into truffles in the palms on the hands or with a teaspoon and roll in the crumbled Gavottes.