I made a 2 layer cake with chocolate butter cream made with real butter. Do I need to refrigerate the cake?
No need to refrigerate (unless you really want to). There's enough sugar in buttercream (at least in American buttercream, I don't know about meringue-based ones) to act as a preservative, even when you use all butter. I've kept buttercream for over two weeks out of the fridge, and I live in the hottest place on Earth, or at least one of them (with no kitchen AC)!
Thank you for the reply, last time I used half Crisco and half margarine and it seemed thicker than this time with real butter which looks more like a mouse on the cake.
You don't even have to refrigerate butter.