How do you bake a pumpkin cake in a bowl?

by Ann Shoemaker
(Warner Robins, GA)

I've seen several picutes of pumpkin cakes where the decorator said she baked two cakes in a bowl and put the two together to make the pumpkin. I tried using a 2 quart aluminum bowl. I put a heating core in the center of the bowl and filled the core with the cake batter. I filled the bowl to about two and one half inch from the rim and baked at 325 degrees for 1 hour and 20 minutes. I finally took it out because the outside was getting over done and center around the cake core was not done. The batter in the heating core barely cooked at all. I used a regular layer cake recipe. What did I do wrong? I tested the temperature of my oven with a therometer and it is correct. Thanks.