I made Martha's IMBC just for the heck of it. I love the taste and texture, but because it's made out of butter, and not the usual crisco shortening recipe I make, I'm worried about how long this can stay out of the fridge, both covered by fondant or uncovered on a cake.

I have a cake due this weekend that has a lot of fondant decorations and will need to be out anyhow once it's covered. I wanted to make the cake on Thursday, decorate and deliver Friday night. Party is Saturday morning.

If you've had experience with this buttercream, please send me some info! Can I use it or just make some crisco buttercream to be on the safe side

TIA!
Mirjana

I don't think it's the butter that's the problem, it's the egg whites. Any frosting made with eggs needs to be refrigerated. If your locale has a big refrigerator that the cake could sit in, that might be ok.