Place the cream and butter into a saucepan and slowly bring to the boil. Remove the boiling liquid from the heat and quickly stir through the chopped chocolate, stirring until the chocolate is melted and the mixture is thick and smooth.
Allow the mixture to coll to room temperature and then place into the refrigerator. Stir the mixture every 5 minutes until it becomes quite thick and hard to stir.
Beat the ganache with an electric mixer until it has increased in volume and has lightened in colour quite considerably. (If the mixture looks as if it may curdle at any stage, place the bowl into a pot of warm water and allow the mix to melt slightly. Then continue whipping with an electric mixer).
Spread immediately over your cake.
This recipe makes enough to cover one 23cm cake
