Preheat your oven according to the recommendations, usually around 350°F (175°C). Pour the prepared batter into a greased baking dish and bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean.

Once baked, allow the cake to cool for about 10 minutes in the pan.

Poke holes evenly across the top of the cooled cake using the handle of a wooden spoon.

Warm the hot fudge in the microwave for about 30 seconds until pourable and gently pour it evenly over the cake.

In a mixing bowl, combine the chocolate instant pudding mix with the milk, whisking until it thickens, about 2 minutes. Pour it evenly over the fudge-covered cake.

Chill the cake in the refrigerator for about 20 minutes.

Prepare the topping while the cake is chilling by mixing any remaining pudding with a little milk and refrigerate until set.

Once set, gently fold in the thawed Cool Whip and mix in about three-quarters of the crushed Oreos.

Spread the Cool Whip mixture evenly over the top of the cake and sprinkle with the remaining crushed Oreos.

Serve immediately or chill until ready to enjoy.