Preheat oven as indicated on the chocolate cake mix box. Combine cake mix with required eggs, water, and oil, and pour into a greased 9x13 inch pan. Bake for 25-30 minutes until a toothpick comes out clean. Cool for 10 minutes.

Use the handle of a wooden spoon to poke holes all over the cake once slightly cooled.

Microwave the hot fudge for about 30 seconds until pourable, then pour it over the cake, filling all holes.

Mix chocolate pudding with 1.75 cups of milk for about 2 minutes until slightly thickened, then pour over fudge layer.

Refrigerate for at least 20 minutes to let the pudding set.

Whisk another packet of chocolate pudding with 1.75 cups of cold milk until thickened, about 10 minutes.

Gently fold in thawed Cool Whip and mix in ¾ of the crushed Oreos.

Spread the Oreo-pudding mixture evenly over the chilled cake and top with remaining crushed Oreos. Chill briefly if needed, then serve cold.