Broken buttercream is the bane of any cake decorator's existence. Many types of buttercreams can "break," but I'm talking about good ol' American buttercream, today. American buttercream is simply a mixture of powdered sugar, butter, vanilla, and a liquid.
So, what exactly is broken buttercream?
Buttercream breaks when the fat and liquid in the recipe separate from each other. It gets chunky/beady and quite ugly. This is what it looks like (I darkened the picture quite a bit to make it easier to see):
Isn't that just ugly? Definitely not something you want to put on a cake.
When I had my first experience with broken buttercream, I turned to the internet to see if there was a way to fix it, or if I would just have to toss it. There were several options to try to fix it, but they weren't very quick or easy. Most of the options included beating the buttercream like crazy for a long time or messing with the temperature of the buttercream until it was just right. Getting the temperature just right involved either heating the buttercream or cooling it down with an ice pack...but if it went too far either way, you would have to keep messing with it. In other words, way too complicated!
So what is the quickest and easiest way to fix broken buttercream?
Add a tablespoon or two of shortening.
That's it! Just add 1-2 tablespoons of shortening and beat for about 30 seconds. That's all it takes! The buttercream will magically come back together as the shortening recovers the balance of fat and liquid. Since it is such a small amount, the shortening does not alter the flavor of the buttercream.
Note: A perfectly good buttercream can also break when food coloring is added. To help prevent this from happening, stick to gel based icing colors instead of liquid based ones.