does a cake that sinks mean it's not done?? I've put toothpicks in all around it and it's done, but the middle still sunk..
10" pan, used nail and baking strips.. cooked it a bit longer than it's twin (came out fine). move the pan to different area in the oven.. now what??
one of the reasons cakes sink in the middle is because it was not fully cooked or deflation from overmixing. another reason could be that something wrong with the leavener (too much of it). sometimes the oven is too hot. if you have a oven thermometer check that you have the correct temperature.