In a large bowl, whip the cake mix, water, oil and eggs with a hand mixer until well combined. Add melted butter and 1/3 cup of the evaporated milk. Pour half of the batter into a greased 13”x9” pan.
Bake 350°F for 15 minutes.
Meanwhile, in a microwave safe bowl, melt caramels and evaporated milk together in 20 second intervals, stirring until smooth.
Remove the par-baked cake from the oven and pour the caramel on top. Spread evenly, then top with butterscotch chips, chocolate chips and pecans. Pour and spread remaining batter evenly on top.
Bake 20-25 minutes or until cooked through. Sprinkle the top with powdered sugar.