Preheat oven to 350 degrees F. and line a 9 x 13 inch baking dish with parchment paper.
Prepare brownie mix according to package directions, stir in chocolate chunks and transfer to prepared baking dish. Drizzle with warmed peanut butter and bake for 28-32 minutes, until baked through. Let cool for 30 minutes before drizzling with caramel.
Place unwrapped caramels into a heat proof bowl and microwave with milk for 30 second intervals until melted and smooth. Drizzle over tops of brownies and sprinkle lightly with salt. Let cool completely then cut into squares to serve.