I love love love Sharon Zambitos buttercream recipe. However, the last two cakes I have done they have cracked. One right in the middle of the side, the second the whole side came apart from the cake!! Any ideas as to why it has started doing this!?

Every time I've had a problem with cracking, it has been because of insufficient support. If your cake base is flexible AT ALL, your icing can crack when you move the cake.

That's what i thought with the first one, so I put this last one on foam core board.... myabe this time was just a fluke.

I add a drop or two of vinegar to Sugarshack's recipe. It helps it from cracking. It's also not noticeable in taste either. But yes if the support isn't enough and you are moving it then it can crack too. Did you run a hot spatula on the cake to smooth it out?

I also think, you need to maybe loosen it a little more with the milk. I have made this also and i add a little more. Yes, sounds like you got the board situation down pat.