Mix dry cake mix, butter, 1/3 c. evaporated milk. And pecans. Spread 2 batter in 9 x 13 pan (greased). Bake at 350 degrees for 10 minutes.
Melt caramel and 2 c. evaporated milk in double boiler or in the microwave.
Sprinkle cake with chocolate chips, pour melted caramels over, then spread with other half of cake mix. Bake 20 minutes more. Sprinkle with powdered sugar if desired.