Preheat oven to 350°F (175°C) and grease a 9x13 inch baking pan.

Prepare chocolate cake batter using the cake mix, eggs, oil, and water according to package instructions.

Pour batter into the prepared pan and bake for 30-35 minutes or until a toothpick comes out clean.

Remove cake from oven and immediately poke holes across the entire surface using the handle of a wooden spoon.

Pour the sweetened condensed milk evenly over the warm cake, allowing it to soak into the holes.

Drizzle the caramel sauce over the milk layer.

Cool the cake completely to room temperature, then refrigerate for 1 hour.

Spread the whipped topping over the cooled cake in an even layer.

Top with crushed Butterfinger candy bars.

Drizzle melted peanut butter over the candy layer.

Refrigerate for at least 1 additional hour before slicing and serving.