Ok I'm so confused. Does Wilton buttercream need to be refrigerated!? Or is it okay to be left out (as a filling in a cake) on the counter?? When I search this on google the opinions are half and half... So confused. Anyone?

amanda I always make the Wilton recipe...but never use milk or cream. Then you should probably refrigerate it. I use water for the liquid or a liqueur that matches the cake flavor. The fat ratio I use is 50% unsalted butter and 50% hi ratio shortening.

I use half salted butter and half shortening (and don't add salt) for my buttercream, and it's fine at room temp for several days to a week.  If you're going to store it longer, you'll want to refrigerate it.