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.