I just made my first big, fondant cake with my son for his Boy Scouts lad and Dad bake sale. It turned out pretty well, I think, but I had a pretty significant problem with the fondant buckling over time and starting to crack. Here's a picture, to show you what I mean:



Thankfully, the nature of a wooden pirate chest means that the flaws are harder to see, but if you look at the sides and edges you can see that it's no longer straight and has started to collapse. On the sides, there were some vertical cracks which were pretty visible.

I made the cakes on Sunday, using a pretty firm chocolate poundcake recipe. I filled and crumb-coated with a simple buttercream on Monday morning (which turned out a little loose due to the extreme Texas heat) and covered the cake a few hours later. It sat pretty well overnight with minimal changes and I airbrushed it on Tuesday morning. By the time of the event on Tuesday night, it was really buckling pretty fast.

The top of the cake, btw, is rice krispy treat cereal and had no problems with buckling or anything.

Any tips or advice? Also, does anyone know of a really good buttercream recipe that holds up well in high heat and high humidity? Or, should I be using something other than buttercream for fondant cakes? Thanks![/img]

Your filling/buttercream might have been too soft. If you are going to use a soft filling you need to make sure you pie a nice stiff damn around the edges of the cake to keep everything inside. I have had this problem multiple times.

I don't know how you supported your cover, but if there isn't the right support where the lid sits it will also collapse your cake.

HTH