thank you for this post.  I have been trying to find an answer as to why the exact same thing has happened to me.  I have been making chocolate mud cake for years.  I use it for carved cake.  I make the ganache with butter and chocolate and syrup and cover the cake with it and let it set hard before I then cover the cake with fondant.  to my knowledge, this has never ever caused mould but at the beginning of the year I was told that the joins had gone mouldy and so had the...