From the Cupcake doctor cookbook, slightly modified!
1 - white cake mix
1/3 cup oil
1/2 cup milk
3 large eggs
1 - 16 oz can sweet potatoes (drained) or pumpkin
1 tsp vanilla
1 tsp cinnamon
1/2 tsp nutgmeg
Mix ingredients slowly for a minute. Then on medium speed for 2 minutes. The sweet potatoes will blend pretty quickly in the mixer. No need mash before hand.
The original recipe calls for an organge glaze, but I prefer buttercream icing. You can use your favorite recipe and add 1/2 tsp of orange extract to compliment the spices. Or vanilla is just as yummy! This icing style is my second favorite. Just use a rounf tip, the largest you have, make a dot and pull. Looks ready for a party, doesn't it?