I always bake & freeze my cakes in advance, but I'm wondering if it's ok to freeze a fully frosted buttercream cake? Will the icing sweat as it defrosts & slide off? Will freezing the buttercream alter the taste of it? I use half butter, half shortening recipe if that has any affect.
I freeze my cakes after baking and iced them frozen but I don't usually put an iced caked in the freezer long term, more than a few hours. It will sweat a lot and any colored piping or decoration will run. If the cake hasn't been wrapped in bags or something really good the icing will taste funny, like it absorbs freezer odors. To me the icing always seems gooey after it thaws out. Experiment with it on small scale, that way if it doesn't work you won't be out anything.
I've frozen completely decorated buttercream cakes and been very happy with the results.
I box the cake, wrap the box in 2 layers of saran and 1 layer of aluminum foil, freeze, defrost still fully wrapped in the fridge for 24hrs. before serving, allow to come to room temp (still wrapped) at least 2 hrs. before serving. No goo, no odor, no sweat, no sliding icing--tastes like just baked & decorated.
HTH
Rae
there is a kind soul on here who often finds these threads and posts about sweating cakes, I can't find her post but she basically says: the cake isn't sweating, it's the change of temperature. Think of a bag of bread. You take it out of the freezer, put it on the counter to defrost. The bread doesn't get wet, but the bag does. So as long as you defrost it wrapped up nice and tight, completely airtight, you should not have that problem.
I have also read a few articles which say it's perfectly fine to freeze a fully decorated cake.
When you make your buttercream color, put a TBS of meringue powder in it.
I've frozen stuff with dark blues, reds and blacks never had any bleeding. Sweat, omg yes!, but no bleeding!
They will sweat; don' touch and don't freak out. They dry themselves out some how.
If you freeze and defrost the cake as I described in my post above, it will NOT sweat.
It can't because it will never be exposed to the humid air in the room while it's still cold--"sweat" is the water in the air forming condensation on a cold cake (just like a glass sweats when it has ice in it).
Rae
Hi Rae, why the box and the foil? I see a lot of people say to use a box, but I'm confused as to why? Why not just the plastic wrap?
Overkill = a guarantee that no moist air will EVER hit the cake before the cake comes up to room temp and no odor will EVER penetrate it.
A box won't ever be airtight and just plastic wrap very well may stick to the icing and mar it when removed.
My method is the "Progressive" insurance--not the minimum state coverage offered by the "General"...... 
Rae
We can "final" (not crumb coat) frost a frozen cake? Then I can add all the decoratons? I am so stressed about crumbs on my final coat 
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