A few weeks ago I made a cake in buttercream. When I awoke the next morning it had a huge bubble on the side! What could cause that to happen?

Lastnight I made a cake and covered it in MMF over buttercream. The same thing happened!

It seems like the buttercream pulled away from the cake!

Any ideas?

Suzette

There are many, many posts about this problem on this site.  There really is no simple answer expect that air/gas got trapped under the icing when you applied it.  This happens all the time to many decorators.  Some have found that by poking  pin holes at the bottom of the cake (all around) it helps prevent/release it. 

I personally found it happened mostly to my smaller cakes as one does not press the icing hard enough to make a good adhearance to the cake because the smaller cakes move when you try.