Preheat oven to 350 degrees F. Generously spray a 9x13-inch baking dish with cooking spray.
Make the cake. In a large mixing bowl, add the cake mix, 1 box of the instant chocolate pudding, eggs, water, and oil. Mix on low until combined, then mix on medium speed for 2 minutes. The batter will be thick.
Spread the batter evenly into the prepared baking dish, and bake at 350 degrees for 20-25 minutes, until a toothpick inserted into the center comes out clean.
While the cake is baking, prepare the topping. In a large mixing bowl, beat together the cream cheese and butter until smooth. Mix in the confectioner’s sugar, and FOLD in the whipped topping until well-combined. Set aside.
In a separate mixing bowl, add the remaining box of instant pudding, and cold milk. Whisk until smooth and allow to sit for 5 minutes in order to set.
Gently but thoroughly FOLD the pudding into the cream cheese mixture.
Once the cake is baked, remove it from the oven, and allow it to cool for 30 minutes.
Once the cake has cooled, carefully spread the topping mixture into an even layer over the cake.
Cover the entire cake with crushed Oreos to resemble dirt.
Refrigerate for 1 hour.
Remove cake from refrigerator, and decorate with Halloween-themed cookies, chocolates, and candies. Get creative!
Serve and enjoy!