Pour some boiling water into a shallow wide-based dish. Place over a gentle heat and allow the water to simmer.
Carefully sit the heatproof bowl in the shallow dish of water. Melt the chocolate slowly, stirring regularly. Remove from heat.
Add the remaining ingredients and mix well. Refrigerate for several hours.
Roll into 15 balls. Refrigerate until ready to serve.
Store in an airtight container and refrigerate for up to 4 days.