Preheat the oven to 350°F (175°C). Grease a 9×13-inch baking dish.
In a large bowl, combine the chocolate cake mix and melted butter until a thick dough forms.
Press the dough evenly into the bottom of the prepared baking dish.
Bake the crust for 12-15 minutes, or until set.

Remove from the oven and pour the sweetened condensed milk and caramel sauce evenly over the warm crust.
Sprinkle half of the crushed toffee bits over the caramel layer.
Return the dish to the oven and bake for an additional 10 minutes.

Let the bars cool completely. Once cooled, spread the whipped topping evenly over the top.
Garnish with the remaining toffee bits and mini chocolate chips (if using).
Refrigerate for at least 2 hours before slicing and serving.
Prep Time: 10 minutes

Cooking Time: 25 minutes
Total Time: 2 hours 35 minutes (including chilling time)
Kcal: 300 kcal per bar
Servings: 12-16 bars