Mashed potatoes surprisingly make this decadent chocolate cake even moister. This surprise ingredient will give your cake a leg up over anyone else's, and everyone will be dying to know what your secret is. This recipe is courtesy of Potato Goodness.
Preheat oven to 350 degrees F. Lightly oil a 9-inch round cake pan and line the base with wax or parchment paper.
Whisk together sugar, oil, and eggs in a large mixing bowl. Whisk in potatoes. Stir together flour, cocoa, baking powder, cinnamon, baking soda, nutmeg, and salt in another bowl. Alternately add the dry ingredients and the buttermilk to the egg mixture, beginning and ending with the dry ingredients and stirring with a spoon or rubber spatula.
Spoon the batter into the prepared pan. Bake until the top springs back when touched lightly, 30 to 35 minutes. Let cool on a rack for 10 minutes. Invert the cake onto a rack and let cool thoroughly. Transfer to a plate and sift confectioners sugar over top.