Step 1: Prep Your Pan and Oven: Preheat your oven to 350°F (175°C). Grab a 9x13-inch baking dish and give it a good spray with non-stick spray.
Step 2: Mix the Batter: In a large mixing bowl, combine the yellow cake mix, pumpkin puree, brown sugar, and pumpkin pie spice. Mix everything together until just combined, being careful not to overmix.
Step 3: Bake It Up: Pour the batter into your prepared baking dish and smooth the top evenly with a spatula. Bake in the preheated oven for about 20 to 25 minutes, or until a toothpick inserted into the center comes out clean.
Step 4: Cool and Poke: Once baked, let your cake cool on a wire rack for about 15 minutes. While it's still warm, use the handle of a wooden spoon (or a skewer/fork) to generously poke holes all over the entire cake, spacing them about 1 inch apart.
Step 5: Drench in Sweetness: Evenly pour the can of sweetened condensed milk over the top of the cake, ensuring it seeps down into all the holes.
Step 6: Chill Out: Cover the cake and refrigerate it for at least 30 minutes. This allows the condensed milk to fully absorb.
Step 7: Top It Off: Once chilled and absorbed, spread the thawed whipped topping evenly over the cooled cake.
Step 8: Add the Extras: Generously sprinkle the toffee bits all over the whipped topping. Then, drizzle the cup of caramel sauce over the top.
Step 9: The Grand Finale (Chill Time!): Chill the cake for a minimum of 3 hours, or even better, overnight. This is crucial for the flavors to meld and the cake to set beautifully. Before serving, drizzle with extra caramel sauce if desired.