Step 1: Preheat your oven to 350°F (175°C). Lightly grease and flour a 9x13 inch baking pan.
Step 2: In a large bowl, combine the yellow cake mix, pumpkin puree, and pumpkin pie spice. Mix on low speed with an electric mixer until just combined and no dry streaks remain. Do not overmix.
Step 3: Pour the batter evenly into the prepared 9x13 inch baking pan.
Step 4: Bake for 28-32 minutes, or until a wooden skewer inserted into the center comes out clean.
Step 5: Remove the cake from the oven and immediately, while still warm, use the handle of a wooden spoon or a fork to poke holes all over the surface of the cake, about 1 inch apart.
Step 6: In a medium bowl, whisk together the sweetened condensed milk and caramel sauce until well combined.
Step 7: Carefully pour the caramel-condensed milk mixture evenly over the warm, poked cake, ensuring it seeps into all the holes.
Step 8: Allow the cake to cool completely on a wire rack, then cover it with plastic wrap and refrigerate for at least 4 hours, or preferably overnight, to allow the flavors to meld and the cake to become thoroughly moist.
Step 9: Just before serving, spread the thawed whipped topping evenly over the chilled cake. Sprinkle with toffee bits, if desired.
Step 10: Slice and serve chilled. Enjoy your amazing Better Than Anything Pumpkin Cake!