1. Preheat the oven to 350°F and grease a 9×13-inch baking dish.

2. In a large mixing bowl, combine the yellow cake mix, pumpkin puree, eggs, vegetable oil, and pumpkin pie spice until smooth.

3. Spread the batter evenly into the prepared baking dish.

4. Bake for 28 to 34 minutes, or until a toothpick inserted into the center comes out clean.

5. Let the cake cool for 10 minutes.

6. Use the handle of a wooden spoon to poke holes all over the surface of the cake.

7. In a bowl, stir together the sweetened condensed milk and 3/4 cup of the caramel sauce.

8. Slowly pour the caramel mixture over the cake, making sure it goes into the holes.

9. Let the cake absorb the mixture, then refrigerate until fully cooled.

10. Spread the whipped topping evenly over the chilled cake.

11. Drizzle the remaining 1/4 cup caramel sauce over the top.

12. Sprinkle with toffee bits and ground cinnamon.

13. Chill for at least 2 hours before slicing and serving.