Heat oven to 350°F (325°F for dark or nonstick pan). Grease or spray bottom of 13x9-inch pan.
Make cake batter as directed on box. Pour half of the batter into pan. Bake 22 minutes. Refrigerate remaining batter.
Meanwhile, in 1-quart saucepan, heat caramels and evaporated milk over medium heat, stirring frequently, until caramels are melted. Stir in pecans. Pour caramel mixture over warm cake in pan. Sprinkle with chocolate chips. Spread with remaining batter. Bake 25 to 28 minutes or until cake springs back when lightly touched. Run knife around sides of pan to loosen cake. Cool at least 30 minutes. Serve with ice cream, drizzle with toppings and sprinkle with pecans. Store loosely covered.