This is from "The Cakemix Doctor". I think I remember making it back when I had to PAY for sweet potatos (gasp!), but I don't know for sure, so I'll make it again!

Sweet Potato Cake with Coconut Pecan Cream Cheese Frosting

1 c mashed sweet potatos
2/3c buttermilk (or use 2 tsp lemon juice + milk to equal 2/3c)
1 plain spice cake mix
3 eggs
1/3 c oil
1 tsp cinnamon

Mix sweet potatos, buttermilk, cake mix, eggs, oil, and cinnamon until well combined and thickened. Place into greased and floured pan. Bake at 350 until cake springs back when lightly pressed, and starts to pull away from the sides of the pan (use cake mix directions as guide, will depend on type of pan you use). Cool for 10 minutes, then remove from pan. Frost.

Coconut Pecan Cream Cheese Frosting

1 container of cream cheese frosting
1/2 c frozen grated unsweetened coconut, thawed
1/2c chopped pecans

Fold coconut and pecans into frosting. Use at once to frost cake.