Combine unwrapped caramels and 1/2 cup condensed milk. Melt together over low heat.
In a large bowl, combine cake mix with melted butter and 1/2 cup condensed milk. Stir until blended. Spread 1/2 the cake mixture over the bottom of a non-stick 9x13 pan. Top with crushed Oreo cookies. Bake @ 350 degrees for 6 minutes. Remove from oven.
Spread the melted caramel mixture over the top of the cake. Sprinkle the caramel with chocolate chips. Crumble the remaining cake mixture over the top of the caramel and chocolate chips. It will not cover completely. Return to oven for 15-20 minutes. Remove from oven. Cool and cut into bars.