The caramel filling adds a deliciously moist texture to the already-soft cake. The sweetened condensed milk thins out the caramel, so it’s better able to squeeze into every nook and cranny.
Preheat the oven and make the chocolate cake according to the package directions, using a 9 × 13-inch baking dish. Let the cake cool for 10 minutes. Using the handle of a wooden spoon, poke several holes all over the cake.
In a liquid measuring cup, combine the sweetened condensed milk and caramel sauce. Pour evenly over the top of the cake, using the back of the spoon to help push it into the holes. Refrigerate the cake for 1 hour.
Frost the top of the cake with the whipped topping. Sprinkle with the pecans and chocolate chips. Drizzle the top with caramel sauce. Slice and serve.