Note to Self: When mixing ingredients for a cake made with butter, please ignore instructions to mix all together at once - remember to cream butter and sugars together thoroughly before adding other.
Today I baked a spice cake; the butter *was* sufficiently softened. The recipe said to mix it all together at the same time, so I did; and no matter how long I made that KitchenAid work at it, I saw small pieces of butter which would not completely incorporate into the batter. I even tried using the whipping beater - nope. I got out my hand-held mixer, thinking I'd have better control; but that didn't do it. The pieces did get somewhat smaller, but they wouldn't disappear. So I had to just hope for the best and bake it anyway. Well, it does look pretty normal - it's in the freezer.
I'm hoping for the best.