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.
Allow 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.
Top with whipped topping and sprinkle additional pumpkin pie spice over the top of the cake.
Notes
Add Nuts: Walnuts or pecans add a nice addition to this cake.
Variation tip: Use Pumpkin Spice pudding instead of the sweetened condensed milk.
Alternate ingredient: Crumbled toffee on top adds a great surprise or finish with a caramel syrup!
Decorate: with cookie pumpkins, maple leaf cookies or fall sprinkles.