Pour the chocolate into a bowl.
Pour the cream and salt into a saucepan then raise to a boil.
Pour the cream mix while hot over the chocolate in the bowl then mix immediately to fully melt and combine.
Mix in the rum.
Let the mix cool in the fridge until cooled totally which should take a few hours, or use the freezer to cool faster.
Spoon out some of the mix at a time to form the balls.
Pour the cocoa powder into a plate then coat every ball in the powder by rolling it in it.