I'm making an eggless cake for a charity event - so it's going to be outside for the day (25 degrees celcius, 72 farenheit). Couple of questions-
1) will buttercream last outside all day?
2) if i cover the cake with sugarpaste / fondant instead of buttercream - can I use buttercream as a filling between layers?
3) if I go with fondant outside, and buttercream inside - how long will the cake last (given I can't put it in the fridge)?
In my experience buttercream should be fine in 72 degree weather. As long as the humidity isnt crazy. And yes you can use buttercream as a filling with a fondant cake. You must crumb coat the cake anyways with buttercream or the fondant wont stick. Secondly the buttercream in between the layers will keep the layers from "slipping" when transporting. The cake should easily last all day with fondant/buttercream as long as the humidity stays down. Hope this helps.
Amazing - thank you so much!