Preheat oven to 350°.
Coat a 12-cup Bundt pan with cooking spray, and dust with flour; set aside.
Combine the sour cream and next 6 ingredients (sour cream through chocolate pudding mix) in a large bowl, and beat mixture at medium speed of a mixer for 3 minutes. Add the chocolate chips, and beat the mixture for 30 seconds.
Spoon the cake batter into the prepared Bundt pan. Bake cake at 350° for 1 hour or until a wooden pick inserted in center comes out clean. Cool cake in pan 10 minutes on a wire rack. Invert cake onto a wire rack, and cool completely. Sprinkle cake with powdered sugar.