You will need about 40 petit four cases on a baking sheet. Measure the rum, raisins, jam, biscuits and cake into a large bowl. Add the melted chocolate and mix together very thoroughly until all of the mixture is covered in chocolate.
Shape into about 40 little truffle balls and roll each one in the chocolate vermicelli strands. Place in the petit four cases.
Leave to chill in the fridge for about 1 hour before eating