I am not sure what caused this cake to undercook on the bottom only. I used a white cake scratch recipe from Cook's Illustrated. It is one that uses reverse creaming. I really enjoy the flavor.
The toothpick came out clean, but that was misleading...when I cut into the cake after cooling, the bottom was undercooked. I checked and my oven temp is okay. I used the middle oven rack.
what the heck?
I'll try to add a pic but I'm not good at that.