Break up the chocolate bar into a glass bowl and place it over a vessel containing boiled water
Use a spatula to mix in a handful of roughly chopped mixed nuts into the chocolate
If you want to use any strong flavours then use a bar of chilli or salted caramel flavoured chocolate or any flavour that takes your fancy
Spoon mixture into coffin shaped moulds and allow to set in the refrigerator for atleast 20 minutes
Once set, they should come off the mould pretty easily
Place them on the graveyard cake however you like
This mixture makes 6 coffin shaped chocolate cake toppers