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 spice cake mix, pumpkin puree, water, eggs, and vegetable oil. Beat with an electric mixer on medium speed for 2 minutes, or until well combined and smooth.
Step 3: Pour the batter into the prepared baking pan and spread evenly.
Step 4: Bake for 30-35 minutes, or until a wooden skewer inserted into the center comes out clean.
Step 5: Immediately after removing the cake from the oven, use the back of a wooden spoon or a skewer to poke holes evenly over the entire surface of the warm cake, about 1 inch apart.
Step 6: Pour the sweetened condensed milk slowly and evenly over the warm cake, ensuring it seeps into all the holes.
Step 7: Let the cake cool completely on a wire rack, then cover and refrigerate for at least 2-4 hours, or preferably overnight, to allow the milk to fully absorb.
Step 8: Once the cake is thoroughly chilled, spread the thawed whipped topping evenly over the top.
Step 9: Drizzle generously with 1/2 cup of caramel sauce.
Step 10: Sprinkle with 3/4 cup of the toffee bits. If desired, drizzle with extra caramel sauce and sprinkle with the remaining toffee bits just before serving.