Grease a 9x13-inch baking pan with butter or non-stick cooking spray. Set aside.
Mix the batter and bake the cake according to the directions noted on the back of the cake mix box. Allow it to cool completely before moving on to the next step.
When the cake is completely cool, use the handle of a wooden mixing spoon to make 3 rows of holes in the surface of the cake, poking 8 evenly spaced holes in each row. Important: Do not poke all the way through to the bottom of the pan! Stop just before the spoon handle touches the bottom of the dish.
Cover the chocolate poke cake with condensed milk, allowing it to fall into the holes. If needed, use a rubber spatula to spread milk into an even layer over the entire surface.
Repeat the previous step using the caramel sauce.
Cover the cake with plastic wrap and place in the fridge for 2 hours before moving on to the next step.
Spread the whipped topping over the cool caramel chocolate cake. Some whipped topping may seep into the holes, this is okay. *Be sure to use enough topping to completely cover the holes and cake surface.
Top with crushed candy bar pieces and place back into the refrigerator to chill for an additional 30 minutes before serving.
Notes
To save time, you can make the cake recipe a day ahead of time. Be sure to let it cool and cover with plastic wrap until you're ready to continue.
To check for doneness, insert a toothpick into the center of the cake, then remove it. If comes out dry or with a few moist crumbs, it's fully baked.
Let the cake cool completely before making the holes to pour the milk into. Otherwise, the warm cake will crumble and stick to the the wooden spoon handle.
Allow at least two hours of chilling time before adding the whipped topping and candy.
Expect some condensed milk to absorb into the poke cake. Do not be alarmed if the holes are not as full as they were when you first added them. This doesn't affect the flavor or consistency. It still tastes better than anything else you can make from a box mix!