Combine caramels and 1/3 cup evaporated milk in pot on stove top. Stir until melted. Combine cake mix, butter and remaining 1/3 cup milk in bowl. Beat with electric mixer at medium speed (2 minutes).
Spread 1/2 of batter in greased 13 x 9 pan.
Bake at 350°F for 6 minutes, cool 2 minutes. Spread caramel mixture carefully over baked layer. Sprinkle with chocolate chips. Drop remaining batter by spoonfuls over all. Bake for 18 minutes. Cool and cut.