Kitchen Aid mixer.?Has this just started happening? Your problem happened to me when I I first got my mixer and was making pound cakes..I found that after mixing the batter if I would take my rubber spatula and stir from the bottom up mixing real well...Look at the batter and you can see if some of it is not blended as well together...I hope I have not really confused you...If you don't understand I will give it another try..Let me Know..