Line a 9x9 square baking pan with foil, allowing ends to hang over the edge of the pan. Spray foil with cooking spray.
In a large bowl, stir the dry cake mix, 1/3 cup evaporated milk, and melted butter until incorporated.
Spread half of the batter into the prepared pan. Place the bowl with the other half of the batter in the refrigerator.
Bake for about 8 minutes. Remove the pan from the oven, sprinkle the chocolate chips evenly over the brownie layer, and set aside.
Add caramels and 1/2 cup of evaporated milk to a medium glass bowl. Microwave in 30 second intervals, stirring between, until smooth. (Or use a double boiler on the stove top to gently melt the caramels.)
Pour the caramel over the brownie base.
With the chilled half of brownie batter, use your hands to flatten small amounts at a time into discs, about 1/8-inch thick. Place the discs of batter over the caramel layer until you have covered the top. (It’s ok if there are some holes.)
Bake for 20-25 minutes. Let cool to room temperature, about 1-2 hrs, then cover and refrigerate for at least a few hours, until ready to serve.
Using the foil, lift brownies out of the pan and cut them into 16 bars and serve.
Notes
Brownies will need to cool for at least 3 hours before serving.