Preheat oven to 350°F. Grease 13X9-inch baking pan.
Prepare cake mix according to package directions. Stir pecans, chocolate chips and vanilla into batter. Pour into prepared pan. Drizzle 1/2 cup caramel sauce over batter; swirl caramel into batter with knife.
Bake 32 minutes or until cake begins to pull away from sides of pan and toothpick inserted into center comes out clean. Cool to lukewarm on wire rack. Garnish each serving with pecans and caramel sauce.