Preheat and Prepare
Preheat your oven to 350°F (175°C). Line a 9x13-inch baking pan with parchment paper or grease it lightly.
Make the Brownie Batter
Prepare the brownie batter according to the package instructions. Set aside.
Create the Caramel Filling
In a microwave-safe bowl, combine the caramel sauce or caramel bits with the butter and milk. Microwave in 30-second intervals, stirring between, until smooth and creamy.
Assemble the Layers
Pour half of the brownie batter into the prepared pan and spread it evenly. Bake for 10 minutes to set the bottom layer.
Remove from the oven and carefully pour the caramel sauce over the baked layer. Spread gently, leaving a small border around the edges to prevent sticking.
Sprinkle half of the chocolate chips over the caramel layer.
Pour the remaining brownie batter over the top and gently spread to cover the caramel and chocolate.
Bake the Brownies
Return the pan to the oven and bake for 20-25 minutes, or until the top is set and a toothpick inserted into the edges comes out clean.
Cool and Slice
Allow the brownies to cool completely in the pan to set the layers. For clean slices, chill in the refrigerator for 30 minutes before cutting.