Ok! I baked the WASC in a full sheet cake pan. Thought the cake was done, looked nice on top; started pulling away from the sides. Well, I decorated the cake, seemed to be just fine. Not gooey in the center. Well I delivered the cake and the customer states that the cake was too hard around the outside and gooey on the inside. Please help. What did i do wrong. I used the original recipe with egg whites.

HI: I would also love to hear from others with this problem. This recipe is delicious but all the sour cream makes it SO moist that I have trouble getting the center done before the edges are TOO done, even when I use the insulating bands.

Have you tried the upside down greased flower nails in the middle or a heating core? You also might want to make sure your oven is calibrated correctly by having an oven thermometer. I find the best thing to do is cook for a longer period of time at a lower temperature. 325 degrees is the max I cook it at, sometimes I even bake it at 300 degrees. I also like to use bake even strips.

......baked the WASC in a full sheet pan......used the original recipe with egg whites.....

My *original* recipe does NOT use egg whites it uses whole eggs.
This sound to me like an oven issue. Have you had the oven checked for calabration lately?
If you think the cake is too moist cut down on the sour cream Use 2/3rds or even 1/2 cup and see if you like that/if it makes a difference.
I do not use wet strips nor flower nail/heat core in my baking but it doesn't hurt if you do.

Yes, I used the flower nail in the center and I bake at 325 for a longer period of time, and I use the bake even strips. I will have to calibrate my oven though.