Prepare the brownie batter: Preheat the oven to 350 degrees F. Coat a 9×13-inch baking dish with cooking spray. In a large bowl, combine the German chocolate cake mix, melted butter, 1/3 cup evaporated milk and vanilla. Stir until completely combined. The batter will be very thick.
Bake the bottom layer: Press half of the brownie batter evenly into the prepared baking dish using your fingertips. Bake for 8 minutes.
Make the caramel filling: While the bottom layer bakes, combine the unwrapped soft caramels or caramel bits with the remaining 1/3 cup evaporated milk in a medium saucepan. Cook over low heat, stirring constantly, until melted and smooth.
Assemble the caramel brownies: Sprinkle the chocolate chips evenly over the partially baked brownie layer. Pour the melted caramel mixture over the chocolate chips. Drop the remaining brownie batter over the caramel in small clumps. It will not completely cover the caramel.
Finish baking: Return the pan to the oven and bake for an additional 20 minutes. The exposed brownie batter should look set and the edges may begin pulling slightly away from the pan. A toothpick test is not reliable because of the gooey caramel and melted chocolate.
Cool and serve: Let the brownies cool for at least 30 minutes before cutting into squares. They will still be gooey after 30 minutes, so allow additional cooling time for cleaner slices.