I have a cake recipe that results in a minor sunken area in the center of its 9 x 13 pan. It has great flavor and crumb and the center is level and a cake tester comes out clean when I remove it from the oven. I bake it for 70 minutes at 325 degrees F on an unglazed 13 x 13 garden tile using a moistened magic cake strip. I use 2.25 teaspoons of baking powder.
I could use some help on how to resolve the problem. Here is what I know:
Baking the cake longer results in unacceptable browning and drying out of the cake’s perimeter.
Over beating the batter eliminates the sunken center but makes the cake breadier due to increased developed gluten.
My choices are:
1. Lower the temperature to 300 degrees F and bake the cake longer hoping that it will not brown or dry out.
2. Increase the baking powder to 2.5 teaspoons and leave time and temperature unchanged.
Any ideas on how to fix this problem?