Hmm... Let me talk to the kitchens tomorrow about this. Until then, I am unsure... I would maybe use an even lower setting for next time. Sincerely, Cate

Feedback from the kitchen. Maybe it could be this?:

Q. What causes a wrinkled top and extreme shrinkage?
A. This may be caused by too much liquid. Be sure to follow the directions on the package and measure carefully. To measure liquid, place a liquid measuring cup on your counter, pour in the liquid, bend down and check the amount at eye level.

Beating the batter too much. Double-check the beating time in the package directions, and use low or medium speed on your standard or portable mixer. If you're beating the batter by hand, beat 150 strokes per minute—it's okay to rest now and then!
Not baking the cake for the correct bake time as specified for each pan in the package directions. If extra ingredients are added to the cake batter (such as sour cream, pudding, etc.), bake times may need to be adjusted.
The oven temp is too high. To check oven accuracy, use an oven thermometer. Follow the package directions to determine if the cake is done.

Hi,

Yup, I did the same thing when I first got my KA mixer. When I read the instruction book more carefully, it stated that beating time is shorter and at a lower speed than standard or hand mixers. That was 20 years ago. By golly, I did the same thing last week. The phone rang and I "overbeat" my cake. It shrank and was tough. I didn't even bother to frost it. Oma