1. Cut the chocolate into pieces. Place chocolate and butter in the bowl fitted with the kneading/crushing blade. Launch at speed 3 at 110°F for 10 minutes.
2. Add the chestnut cream and mix at speed 10 for 30 seconds.
3. Pour the mixture into a 1 1/2-quart baking dish; cover and refrigerate for at least 2 hours.
4. Dip small spoonfuls of this mixture in the cocoa powder and roll into balls using your hands. Store in the refrigerator.