Preheat oven to 350°F (175°C) and grease a 9x13-inch baking pan with non-stick cooking spray.

In a large mixing bowl, combine the spice cake mix, pumpkin puree, eggs, vegetable oil, and water. Beat on medium speed for 2 minutes or until well combined.

Pour the batter into the prepared baking pan and smooth the top with a spatula.

Bake for 28 to 32 minutes, or until a toothpick inserted into the center of the cake comes out clean.

Remove the cake from the oven and, while still warm, use the handle of a wooden spoon to poke holes across the entire surface of the cake at 1-inch intervals.

Stir the sweetened condensed milk and pour it slowly over the cake, allowing it to soak into the holes.

Drizzle 3/4 cup of the caramel sauce evenly over the milk layer.

Allow the cake to cool at room temperature for 30 minutes, then cover and refrigerate for at least 2 hours to set.

Spread the thawed whipped topping evenly over the chilled cake.

Drizzle the remaining 1/4 cup of caramel sauce over the top and sprinkle evenly with toffee bits before serving.