I have done this before as a filling but the cake was eaten immediately. If I use ganache as a filling and under MMF does the cake need to stay refrigerated? Will the ganache seperate or go bad because of the cream if left at room temperature too long?
In my experience no, it will not go bad or curdle. I've left a cake out for days and it is fine. I believe it has something to do with the amount of chocolate to cream. It seems to stabalise it. I don't know the science of it, but it is my prefered icing/filling to use under fondant for that reason.
Thank you for your advice