Icing--when does it need refrigeration?
I'm never sure when an iced cake needs to be refrigerated or not, and many recipes don't seem to specify this. I prefer to not refrigerate cakes because I believe that it dries them out. But I do not want the icing to go bad. For instance, does a powdered sugar icing made with butter and milk need to be refrigerated? How about one of these buttercream icings that are cooked on the stove then whipped? (I have never made this kind, but will probably do so sometime.) As far as I know, cream cheese icing needs to be refrigerated. What about sour cream icing? Any guidance/rules in this area would be appreciated.
It depends how long the cake will be out and what the temperature is, but usually a powdered sugar icing does not need refrigeration. A buttercream often will, as most of the buttercreams I make have raw egg white in them. They keep about three days in the fridge. You're definitely right though about cakes drying out! Usually I try to keep fridge time to a minimum once iced, so I wait until the last minute to ice the cake if using a buttercream.