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

In a large bowl, combine cake mix, pumpkin puree, egg, oil, pumpkin pie spice. Mix until smooth.

Pour batter into prepared pan and bake for 27-30 minutes until set and springy.

While cake bakes, stir together sweetened condensed milk and caramel sauce. Set aside.

When cake is done, poke holes all over the surface using the blunt end of a wooden spoon.

Slowly pour the condensed milk and caramel mixture over the hot cake, ensuring it soaks into all holes.

Refrigerate the cake for 15 minutes to cool slightly.

Spread whipped topping evenly over the cake surface. Sprinkle with toffee bits and chocolate chips. Drizzle with caramel sauce.

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