I had some big cake problems this weekend. I had an order for smash cake and 6 dozen cupcakes. I made the cake ahead of time, on Tuesday I think. I leveled the two layers and did a crumb coat and stuck it in the freezer until Friday. I frosted it not long after I took it out of the freezer.  A few hours later these bubbles/bulges started forming in the frosting. I am guessing it was because my cake edges were really moist, would that make sense? I baked the 2- 6 inch cakes for about 24 minutes, did the tooth pick test and it was clean so I took them out. I did use baking strips, I love those things but maybe they overlap too much on such a small pan? This morning I had to make a whole new cake. I didn't use the baking strips and I may have baked it a little longer than necessary, I just wanted to ensure this cake wasn't going to basically fall apart as well. I wasn't too worried about it being a little over done since it was just a smash cake. I cut into the bad cake and the frosting had just completely separated from the cake in those funny areas. So, you experienced bakers out there... does my problem stem from underbaked/moist edges or frosting when frozen..or something else I'm not thinking of.

The first picture is my messed up cake and the other is the new with the cupcakes.

Hii,

Okay so, I'm assuming you used American buttercream as this only has happened to me using that buttercream. basically its not that you've under-baked your cake. Did you frost your cake when it was frozen? the thing with cake is that once its frozen it slightly shrinks and basically as it comes to room temp it rises up again, and as it does that it releases air/gases (lots of air in there remember all the mixing). American buttercream once hot knifed forms a film that kind of seals the cake. at this point if you try to remask or even run your spatula on it the icing will peel off because it forms a slight crust. think of it like hot tea with cream the forms a smooth film at the top once it cools. and if you touch that film it folds on top of each other. 

At that point American buttercream also is kind of wet on the cake (not outside the frosting film). this is because of the condensation, and bubbles appear because of the air. since there is no way for the air to escape it besides expanding it does just that, and that creates your bubbles. 

Freezing cakes are fine, just if you are masking using ABC, mask the cake when its cold but not frozen. not even a little bit frozen. I actually advice the same with using any buttercream just to be safe. 

If you want to experiment take a picture of a frozen cake at eye level and then thaw that cake up to room temp and take a pic to compare. 

Its really not that you did something wrong, its just all the baking chemistry messing with you haha 

Hope I helped. xo

The problem was that the cake was still fzn  &in a hurry so the icing didn’t get pushed against the cake well enough    Also such small cakes are hard to ice   They tend to slide around so you don’t get the icing tight enough attached to the cake allowing air pockets to develop   It has nothing to do with the baking nor the type of ining used     BTW  the edges were moist because it was baked right - not under baked 

Oh,& another thing- if it ever happens again you can use a pin to let that trapped air out then gently push the icing back down   Just make sure your layers are level so trere’s no air space for bubbles to form 

cake farts, aka cake bubbles, happen in all kinds of temperatures and all kinds of holding methods and with all kinds of icing -- they maybe happen more with some methods/icings/temps more than others but any of it can produce a cake fart --

a form of insurance is to on purpose put a small hole about the size of a wooden dowel into every cake layer through the icing into the cake and keep it open -- hidden behind a flower or placed in the 'back' of the cake -- so the trapped air has a hole to escape if it needs it -- 

I always ice frozen cake -- I usually forget to put the holes -- but one place i worked i had to put them in all their tier cakes that went out -- happens if everything is kept room temp too -- it just happens

yeah sucks -- sorry

perfect recovery though -- well done 

Thank you for the in depth explanation HudaM! I will be sure to never frost a frozen cake again.  Or if I do, I will poke holes in the cake to allow the air to escape like K8mephis said. Cake fart, that's funny. Ill share that one with the men in my family, they'll enjoy that!
I feel like I really got the buttercream pushed against the cake. I used a cake scraper to smooth which I feel like using alot of pressure and then also the viva paper towel trick using a fondant smoother to press against the cake.

Gosh I really hope the new cake I made is doing fine. It's all I've been thinking about. I hope that cake didn't fart and that I pressed the buttercream well enough to the cake. Luckily I know the people decently well and they love to take a million pictures of events and post on Facebook. I should be able to catch a glimpse of everything I did and see how it held up. Fingers crossed! I've been fighting with myself NOT to text and just check in on the cake. I'm such a worrier. I don't know if I could get into making cakes if this is how I'd feel all the time. Cupcakes are so much easier. Though sometimes I have problems with my buttercream looking greasy and have yet to figure out why...

I did try to repair the first cake. I completely removed a glop of frosting where the bottom bubble is and it just came back. 

........I feel like I really got the buttercream pushed against the cake. I used a cake scraper to smooth which I feel like using alot of pressure and then also the viva paper towel trick using a fondant smoother to press against the cake. ..........

Well so much for my old fashioned advice LOL

Kakeladi, your advice is good and very much appreciated! And I'll always be thinking about that as I frost future cakes. It just hadnt crossed my mind since it seemed like I applied a lot of pressure..

all good -- just so you understand that even cakes that have never been frozen do this --

and that I have iced my cakes frozen for decades