Hello all. I am really new at this. I just made a barbie cake. The barbie turned out great, but the sheet cake under it didn't. I covered the sheet cake with buttercream frosting. After it set, it had lots of cracks in it. Is there anything that I can do to prevent this?

P.S. I kept it on a flat surface and was very careful when picking it up. lol

Heavier board/boards for stabilizing it, and add a touch of vinegar to icing..doesn't alter taste, no worries

icing might have been a bit too dry as well