I have a request for a chocolate cake with a chocolate ganache filling. I have not used ganache very much and was wondering if the ganache should be whipped before filling? Also, if it needs to be whipped, will it get runny if the cake is not refrigerated?
I fill my cakes with unwhipped ganache all the time.
A straight ganache with a 2:1 ratio will be pretty firm as a filling, a bit like a thick fudge. I've whipped it a time or two also, most recently with Bailey's added. While it was quite a bit lighter than straight ganache, it wasn't runny - and I never refrigerated it.
Whipped or unwhipped - probably depends on what you're looking for. I personally prefer the ganache unwhipped. It makes for a knock-your-socks-off thick, rich, intense, chocolate overload cake. (Then again, I do go overboard, torting with it too. I used every little bit of 4 pounds of chocolate - and could have used more! - in the top and bottom tiers of the school cake I just did. But I digress...)
I don't know how whipped ganache behaves when refrigerated, but if you go the unwhipped route, you'd be wise to keep it away from the fridge. Unless you want to cut the cake with a chainsaw.
No, it won't get runny if you don't refrigerate whipped ganache...I prefer to not refrigerate mine (esp if there is unwhipped ganache) because it can get a little hard.
I prefer to use whipped ganache as a filling because it is closer to an icing consistency so it feels more natural with regular cake. Just remember that whipped ganache really does need to chill at least over night before you try to ice with it, while regular ganache can be prepared just before use.
It's a matter of preference. Whipped is a bit more like buttercream. Either or is good, it's what you like the best the only thing that will change the finish product