Preheat oven to 350 degrees F. Grease bottom and sides of 13x9x2 pan. Make cake mix as directed on package using water, oil, and eggs. Pour half of the batter into pan. Bake 25 min.
Meanwhile, heat caramels and milk in 1-quart saucepan over medium heat, about 10 minutes, stirring frequently until caramels are melted. (Or place caramels and milk in 4-cup glass cup. Microwave uncovered on High 2 minutes to 3 minutes 30 seconds, stirring once or twice.)
Pour and spread caramel over warm cake in pan. Sprinkle with pecans and chocolate chips. Spread with remaining batter. Bake 30 minutes.
Run knife around side of pan to loosen cake. Cool completely about 1 hour or serve warm with vanilla ice cream. Serve with additional chopped pecans and drizzle with chocolate or caramel syrups if desired.