Preheat oven to 350℉ and place 18 cupcake liners in muffin tins; set aside.
Prepare the cake mix according to the box instructions.
1 box Devil's Food Cake mix
Fill each of the muffin liners about 2/3 full.*
Bake for 14-16 minutes, or until a toothpick pressed into the center of the middle cupcake comes out clean or with just a few moist crumbs.
Use a straw or the handle of a wooden spoon to poke 5-7 holes into each cupcake, poking about 2/3 the way down.
Remove the cupcakes from the pan and let them cool on a wire rack.
In a microwave-safe bowl, combine the caramel and sweetened condensed milk.
1/2 cup caramel topping, 1/2 cup sweetened condensed milk
Microwave on high for 30 seconds and stir (it should be warm and runny).
Use a spoon to slowly pour the filling into the holes of each cupcake and spread a little on top.
Sprinkle the cupcakes with about 1/2 cup of the toffee pieces and refrigerate for at least an hour.
1 cup chopped toffee pieces (ie Heath Bits)
In a large bowl, whisk together the milk and pudding mix (it'll be very thick).
1 3.9-ounce box instant chocolate pudding mix, 3/4 cup milk
Add a spoonful of the whipped topping and whisk until combined. Add the remaining whipped topping and stir until combined.
1 8-ounce tub whipped topping
Spoon the topping over the cupcakes and sprinkle with the remaining toffee pieces.
Drizzle with additional caramel, if desired, right before serving.