I've made this recipe about 10 times before in the past. Two days ago, I attempted to make it using the same recipe I always have (http://cakecentral.com/recipe/italian-meringue-buttercream-imbc) and it turned out like soup! I tossed it in the fridge thinking it might firm up, but it never reached a texture that would hold any shape. I tried again for a second time, double checking all my measurements and times, and AGAIN it turned out like soup. This morning, I made a third attempt...and now I'm completely frustrated and out of ideas. The meringue turns out fine, nice and thick, until I add the butter. I soften the butter in the microwave for about 20 seconds before I add it in. I'm hoping someone has had this happen before, or can give me some suggestions on what I'm doing wrong this time around.
You have to find the change.
Did you change butter brands? Off brand butters have more water?
The big one... check your thermometer. They can go out of calibration in one use. If it is digital, it cannot be fixed. My Taylor actually slipped in its metal casing, probably from overuse. I now have it taped with electrical tape. A low temp can cause the syrup to not change into the confection needed to make the IMBC. Too high and the syrup may have an adverse effect due to a chemical change different than needed in IMBC.
Is your mixer running hot and giving off heat at the head?
Feel your butter. Is it too soft?