I have a couple quick questions because I am desperately afraid of making everyone sick at my sister-in-law's baby shower. I have to travel with the cake on Friday afternoon and the shower is on Saturday. I wanted to complete the decorations on Friday morning, so I wanted to have the cake frosted and covered with fondant on Thursday. I am going to fill it with buttercream and cover it with white chocolate ganache and then fondant. Will this be ok sitting out from Thursday to Saturday? I wish I could do it fresher, but logistically, there is just no way. If my buttercream has cream in it, will it spoil?
You should be fine. There's so much sugar in buttercream that it helps keep it from spoiling. As for the ganache, I've read both ways - that it's totally ok out of the fridge, and also that it depends on how much cream you used, something about spores, etc. But, with that being said, I have had to do a few cakes with buttercream AND ganache on Thursday nights for pick up on Friday evenings (I work a regular job during the day), with a party on Saturday and I haven't had any complaints. I leave my cakes on the counter and don't refrigerate them. That's just me. If anyone else has had a problem with it, I'd like to know so I can avoid it in the future!
If you're making the standard ganache for filling (2 parts dark or milk chocolate OR 3 parts white chocolate to 1 part cream, by weight), it won't spoil and you probably don't want to put it in the fridge because it will get rock hard and will be hard, if not impossible, to cut -well, not if you take it out several hours in advance, of course, but there's really no need to refrigerate.