Preheat oven to 325. Grease and flour 13x9 cake pan
Prepare cake mix according to package directions
Spoon half of batter into prepared pan. Bake at 325 for 20 minutes. Cool cake for 5 minutes.
While cake is baking, combine caramels, butter, and sweetened condensed milk in saucepan. Cook over low heat, stirring occasionally, until caramels melt. Then pour and spread over cake.
Spread remaining batter evenly over caramel layer. Sprinkle pecans and chocolate chips over top. Bake at 325 for 30-35 minutes. Then turn oven off, leaving cake in oven for 10 more minutes. Remove cake from oven and cool. Cut into squares to serve.