Hi all since its summer ive been playing around with more stable icings.well i was wondering how long can half butter half high ratio shortening buttercream sit out under a fondant covered cake? will it start to slide or melt in warmer temps? also how can i kill some of that super sweet powder sugar taste you get with this type of buttercream? thanks all!

Buttercream does not like heat or humidity. If you are warm and sweaty, then your buttercream is probably warm and sweaty too. A fondant covering would protect it some what. I am sure you can imagine the temperature it would take to make butter start to get soft and I think that would be a good indicator as to when your icing would start getting soft under fondant.

I have found that swapping out some of the meringue powder, with equal measure corn starch, helps tremendously.

I honestly don't know if you can kill the super sweet sugar taste in buttercream. Sometimes a little fresh lemon juice cuts sweetness. The lemon would add to the flavor of the buttercream. I would adjust it into the liquid amount you are adding to the buttercream, but probably no more then a tablespoon.

My buttercream icing (and I do not stray from my favorite recipe) is half butter, half shortening. Most of my cakes are covered with buttercream, including wedding cakes. I live on the Outer Banks of North Carolina where the temperatures have been in the high 90's and the humidity is almost always near 80%. I work on my cakes in the air conditioning, and I suggest my customers keep their cakes air conditioned, not refrigerated. The humidity is so bad here, that refrigerating cakes and then bring them out causes condensation.

I hope this helps,
tokazodo,
Cake Hatteras