Preheat oven to 350F. Line a 9×13-inch pan with aluminum foil and spray with cooking spray; set aside.

In a large bowl, combine the cake mix, pumpkin puree, egg, oil, and pumpkin pie spice. Beat with an electric mixer on high until smooth, about 3 minutes.

Bake for 27 to 30 minutes, or until the cake is set in the center, springy to the touch, and a toothpick inserted in the center comes out clean or with few moist crumbs.

While the cake bakes, combine the sweetened condensed milk and caramel topping in a bowl. Mix well and set aside.

Once baked, use the back of a wooden spoon to poke holes all over the cake, approximately 60 evenly spaced spots.

Pour the caramel mixture evenly over the hot cake, allowing it to seep into the holes.

Refrigerate the cake for 15 minutes to cool slightly.

Spread the whipped topping over the cooled cake. Sprinkle with toffee bits, mini chocolate chips, and drizzle with salted caramel sauce.

Cover and refrigerate for at least 2 hours or overnight before slicing and serving.