I've only made this once before and it turned out perfect! Of course that was when I was just making it to try a new recipe and didn't need it for anything in particular! Now I'm trying to make my son's birthday cake for tomorrow and the icing isn't getting thick and I've whipped it FOREVER! I don't know what I did wrong. I even added more than a cup extra of PS, but maybe it needs more? It's been in the fridge for an hour, hoping it would thicken up by some little fairy in the fridge, but no luck.
Has anyone else had this problem with the house buttercream? Did more PS do the trick? I really don't want to start over and waste all of this butter and PS. Ugh.
I had the same problem recently. I tried 3 different batches and they all came out runny. Wish I could be more help.