I saw this today on food tv. It rocks!
3 1/2 cups all-purpose flour
1 cup sugar 2 teaspoons baking powder
1/2 tsp baking soda
1/2 tsp ground cinnamon
1/2 tsp salt 2 large eggs, lightly beaten
1 cup sour cream
1 cup cooked mashed sweet potato (about 1 medium potato) Vegetable oil, for frying
1 cup finely chopped pecans
2 2/3 cups confectioners' sugar
3 to 4 Tbs milk
1/4 tsp maple extract
In a medium bowl, combine flour, sugar, baking powder, baking soda, cinnamon, and salt. In a large bowl, combine eggs, sour cream, and sweet potato. Gradually add flour mixture, stirring to combine. Turn dough out onto a heavily floured surface. Knead in flour with hands as needed (dough will be sticky). Roll out dough to 1/2-inch thickness. Cut out dough with a 2 1/4-inch round cutter. Cut out center of doughnuts with a 3/4-inch round cutter. Re-roll dough as needed.
In a Dutch oven, heat vegetable oil over medium heat to 360°F. Cook doughnuts, in batches, in hot oil, 2 minutes per side, or until lightly browned. Drain on paper towels. Ice top of doughnuts with Maple Icing, and sprinkle with chopped pecans.
In a small bowl, combine confectioners' sugar and 3 tablespoons milk; stir well. Add additional milk to reach desired consistency. Stir in maple extract.