I made some of Rose’s Milk Chocolate Buttercream yesterday and it turned out wonderfully….it was shiny and smooth hours afterward. When I wanted to use some leftover icing later, however, even though it was shiny, it was a bit too stiff to spread. So I reheated it in a double boiler and then applied the icing once it was cooled. Within minutes, it had turned dull, rather than shiny in appearance.
Obviously, I had botched the reheating by letting the icing melt. The question is, what caused the failure? Was it an emulsion failure or did I allow the sugar to crystallize at too high a temperature? The latter sounds more likely, given the change in appearance. But when originally making the frosting, the chocolate melted, too, without affecting its later appearance. However, there was some unmelted chocolate in the original batch when taken off the heat, and I understand that mixing tempered chocolate into melted chocolate can help create small crystals.
Basically, I want to know what I did right the first time that I didn’t do when reheating. I’d also like to know how I could have fixed the icing once messed up.