Prepare the cake:
Make the chocolate cake according to the package instructions, baking it in a 9×13-inch pan. Allow the cake to cool completely before moving on.

Create the poke holes:
Using the handle of a wooden spoon, gently poke rows of holes all over the cooled cake to allow the pudding to seep in. Set the cake aside.

Prepare the pudding:
In a medium bowl, whisk together the Oreo cookies n’ creme pudding mix and cold whole milk for 1–2 minutes, or until the pudding begins to thicken.

Fill the cake:
Pour the thickened pudding evenly over the top of the cake, spreading with a spatula to fill all the holes. Make sure the pudding covers the surface completely.

Chill:
Place the cake in the refrigerator for at least one hour to let the pudding set and soak into the cake.

Finish the topping:
Before serving, spread the thawed whipped topping evenly over the entire cake. Sprinkle the crushed Oreo pieces on top for added crunch and decoration.

Serve and enjoy!