Boil and mash sweet potatoes and set aside.
In a large mixing bowl, add flour, baking powder, cinnamon, and sugar. Add shortening and blend well. Add sweet potatoes. Mixture will get "tacky." Pour onto a floured countertop and roll into a tube. Pinch off dough and press into lightly greased pan. Bake for 25 to 30 minutes at 350° F.