Preheat the oven to 350 °F (177 °C). Spray a 9X13 inch baking dish with non-stick spray.
Mix the pumpkin puree, yellow cake mix, brown sugar, cinnamon, ginger, and nutmeg in a large bowl. (Feel free to use a stand or hand mixer for this step.)
When the batter is fully combined and smooth, pour it into the prepared baking dish. The batter is a bit thicker consistently so use a spatula to spread it evenly.
Bake for 20-25 minutes. A toothpick inserted should come out clean.
Allow the cake to cool (in the pan, on a wire rack) for 15 minutes.
Use the round end of a wooden spoon or spatula to poke holes about every inch on the top of the cake (you don’t need to poke all the way to the bottom).
Pour the sweetened condensed milk over the cake, allowing it to fill all of the holes. It will soak into the cake.
Place the cake in the fridge for at least ½ an hour.
When you remove the cake from the fridge, spread the cool whip all over the top.
Sprinkle the toffee bits over the top. Finish off by drizzling on the caramel sauce.
Then place the cake back in the fridge and allow it to sit for a minimum of 3 hours. (It is best made the day ahead and left in the fridge overnight.)
Notes
Store this cake covered in the fridge for up to 5 days. If you are going to freeze this dessert, do not put on the frozen whipped topping, caramel sauce, and skor bits until you take the cake out of the freezer. Take the cake out of the freezer the day before you are going to use it. Put on the frozen whipped topping, caramel sauce, and skor bits. Then put it into the fridge at least overnight.