Grease and flour a 10-inch fluted tube pan. Set aside.
In a large bowl, combine the dry cake and pudding mixes. Add eggs, sour cream, milk, and cooking oil, stirring until batter is almost smooth.
In a small bowl, combine granulated sugar, nuts, cinnamon, and cocoa powder.
Pour half of the cake batter into the prepared pan. Top with the nut mixture. Top with remaining batter.
Bake in a 325 degree F oven for 55 to 60 minutes or until a wooden toothpick inserted near the center comes out clean. Cool in pan on a wire rack for 10 minutes. Remove from pan and cool completely on a wire rack. Sprinkle with sifted powdered sugar. Makes 12 servings.