Ok, I'm no expert at making cakes, but I've done some. I'm just a small, on the side kind of caker doing about 80 cakes a year. But this one from this past weekend was a total flop and I have no idea what I did wrong.

No recipes were different; same cake; same buttercream; same fillings; same fondant. All methods were the same; same temperatures; same everything!

It was a 2 tiered cake. When I applied the fondant onto the bottom tier, all went well. Great - let's move on to the top tier. Instant disaster. The fondant kept bubbling up all over the place while the buttercream underneath kept suddenly sliding off of the cake causing the tier to have this flared out look. As I tried to smooth it, it would just squish out the bottom. Before I knew it, there was no icing at the top portions of the sides of the cake and these areas were all puffing up with air! I was having fits!! No idea what was going on! When I finally was about to throw in the towel, I looked at the bottom tier and it was doing the same thing! It wasn't to the extent as the top tier but it was there!

Why on Earth did my buttercream react this way when it never has before? My fondant is rolled very thin so it's not like it's too heavy or anything; besides, it was the same fondant techniques I use on every other cake.

The gal ended up loving it; even hugged me for it. But in the back of my mind all I can think is "can she not see that horrible thing??"

I've never seen anything like this. I could just stand and stare at the thing and watch it morph before my very eyes. All when it's due to be delivered in a matter of hours down to minutes.

Any thoughts?

Its hard to trouble shoot this one if you did the same thing you've always done. I only fondant a well chilled (overnight), completely iced cake. I've never had sliding, buldging or any problems. I have had an air bubble that tried to grow but I just pierced it with a pin and kept going. There must of been an ingredient issue or temperature issue along the way? In your buttercream maybe? Did if "feel" the same when you were icing your cake?

Cake civilians can be our best friends (in this case) or our worst enemies. Hope you get it figured out.

I'm no expert myself. I bake less cakes then you do in one year. Although I have never had the problem you mentioned with the buttercream, I have heard of others who have. This may have been caused by whatever you used to coat the cake pan. Did you leave the cake too long in the pan to cool? This may have caused too much grease on the outside of the cake which caused the buttercream to slide right off.

The only thing I can think of is was their possibly their was moisture on the outside of the cake. Possibly condensation.

Thank you all for your thoughts on this! I made a small cake that afternoon after posting this. I used the what was left of the batch of fondant from the cake I had issues with. I saw ONE small pocket of air starting to form, but I was very easily able to remedy that situation. Nothing like that other cake at all! But, that being said, I can't imagine the fondant was the issue; had the buttercream not started to slide off the cake, it would have been fine (I think). The big air pockets were like a suction effect as well. It was just so weird.

It's one of those cakes that I just HATED and couldn't wait to deliver it and never see it again!! While the gal loved it and some select folks I've shown the pictures too, it's one of those ones that I just can't even stand to look at, therefore will not post pics on my site, etc. Surely I'm not the only one that does that! :p haha

Anyway, the only thought I had was, is it possible to have too MUCH buttercream? I don't know that I did that but I suppose it could have been just a little too much? I guess I think about it a lot and start grasping for ideas.

To answer your questions: when I iced it and placed the fondant it did "feel" the same. I thought all was going as planned until I stood still and just watched it for a few minutes before it started to morph. As far as leaving them in the pans too long, I followed the same procedure as I always have... and I used the same product to coat my pans...

These kinds of things are just so frustrating! It ALMOST makes me want to redo the whole cake just to redeem myself in my head. (keyword: ALMOST :p )

Thanks again to all of you!!! You have been most helpful!!