Preheat oven to 350 degrees.
Spray a 9x13 cake pan with non-stick cooking spray.
Add cake mix, pumpkin and milk to bowl and mix until combined.
Transfer mixture to prepared cake pan.
Bake for 30 minutes or until a stick inserted into the middle of the cake comes out clean.
All cake to cool for 10 minutes.
Meanwhile, add pumpkin pie spice to sweetened condensed milk and stir to combine.
When cake has cooled slightly, use the handle of a wooden spoon to poke holes all over the top of the cake.
Pour the sweetened condensed milk mixture over the top of the cake allowing it to seep into the holes. Use a spatula to spread the mixture into the holes if needed.
Allow cake to cool completely.
Top with whipped topping and sprinkle additional pumpkin pie spice over the top of the cake.