Recipe :
Break the chocolate into small pieces in a bowl, then melt over a pan of boiling water.
Split vanilla pod open lengthways, scrape out seeds with the point of a knife.
Mix cream and vanilla together in a pan, bring to the boil.
Pour into bowl of melted chocolate, mix well.
Add melted butter, stir in with a wooden spoon.
Chill.
Add cocoa powder, make mixture into balls.
Roll in rest of cocoa powder before serving.