- Preheat oven to 350 degrees Fahrenheit.
- Prep a 9 x 13-inch cake pan by spraying with baking spray.
- Set aside cake pan.
- Prepare cake mix following the directions on the back of the box.
- Transfer the prepared cake into the cake pan. Set aside (you will be leaving this cake mix unbaked for now).
- Whisk together the pumpkin puree, evaporated milk, heavy cream, eggs, brown sugar, and pumpkin pie spice. Continue to whisk until it is smooth.
- Gently pour this mixture over the unbaked cake mix.
- Take the cake/pumpkin pie pan and transfer it to the oven carefully.
- Bake at 350 degrees for 50-60 minutes.
- (Check to make sure the cake is done by inserting a toothpick in the center. If it comes out clean the cake is set.)
- Add the pudding mix into a large bowl, add the pumpkin spice, and pour in the milk.
- With a whisk begin to mix the ingredients until it begins to thicken.
- Add the cool whip, gently fold it in until it is completely combine.
- Scoop it all on top of the cake and spread it over the entire cake.
- Chill the cake. Keep it in the refrigerator until ready to be served.