Preheat oven to 350°. In a large bowl, combine the first seven ingredients; beat on medium speed until smooth. Pour into an ungreased 13x9-in. baking pan. Sprinkle with dry cake mix. Drizzle butter over top; sprinkle with pecans.
Bake 50-60 minutes or until a toothpick inserted in center comes out clean. Cool 1 hour on a wire rack.
Refrigerate 3 hours or overnight. Remove from refrigerator 15 minutes before serving. Cut into bars. If desired, serve with whipped topping. Yield: 16 servings.