I used heavy cream to make my chocolae buttercream frosting last night. I usually use milk. I don't usually put my cakes in the fridge and left it out. Is it still okay or should it have been refrigerated? Will be delivered this evening.
no need to refrigerate, all that sugar acts as a preservative
assuming that its a crusting buttercream so you only had a couple of tablespoons of cream in there it's ok. No worries since the sugar acts as a preservative (as mentioned above)
I found a great site explaining this. Micro-organisms need water to grow. Because of the high content of sugar & fat in buttercream, water is bound in such a way that micro-organisms cannot utilize it, a.k.a. water activity control.