Combine first 3 ingredients; set aside.
Beat cake mix and next 4 ingredients at medium speed with an electric mixer 2 minutes or until blended. Pour one-third cake batter into a greased and floured 12-cup Bundt pan. Sprinkle with half of brown sugar mixture. Repeat layers twice, ending with batter.
Bake at 325° for 45 minutes or until a wooden pick inserted in center comes out clean. Cool in pan on a wire rack 10 minutes. Remove from pan, and cool completely on wire rack. Garnish, if desired.