I haven't ever had this happen! But I did today twice!!!!!!!! Talk about a waste of money! I can't think of what I did wrong other than maybe I need to give it more time to cool prior to adding the butter. ANY suggestions????
I've had IMBC stay in the curdled stage, even after I beat the heck out of it for what seemed like an eternity. I put the bowl in the fridge for about 4 hrs (once I left it ovenight), and then came back and started beating again. After it had a rest time in the fridge it came back after about 10 to 15mins. Hopefully that works for you too, short of dropping it on the floor I couldn't bring myself to toss all of those ingredients I'm way to cheap for that, I would even try tossing it into a cake batter before throwing it out .
If it looks like cottage cheese, the butter was too cold when you put it in. Wrap a hot, wet dishtowel aroung the bowl and beat it until it comes back. Keep reheating the towel if you need to.
If it looks like wet slop then the meringue was still too warm when you put the butter in. Either put the bowl in the fridge and let it cool down for a while, then beat it again, or stuff bags of frozen peas (or whatever other frozen food you have) all around and under the mixing bowl, and beat it until it cools down. That takes longer than warming it up, but it will work eventually. The buttercream won't be as light as it would be if it worked the first time, but it will be okay to use.
By the way, you know you're a real cake geek when the sight of a curdled buttercream coming back to life is the coolest thing you've ever seen (IT really IS neat to watch, I swear...)
That's a Big LOL!
The first time I made it, I knew what to expect, as I had seen the IMBC coming to life in a video, but I was totally fascinated when I saw it live and in person!
I even yell at my kids to come over and watch it, but they're usually not impressed...