Pour milk into a shallow bowl. Dip each Oreo cookie quickly in the milk (just a few seconds) to soften slightly.
Arrange 30 dipped Oreos in the bottom of a 9x13 baking dish.
Spread one entire tub of Cool Whip evenly over the Oreo layer.
Repeat the process two more times: dip 30 Oreos, layer them in the dish, spread Cool Whip on top.
Your final layer should be Cool Whip. If desired, drizzle with chocolate sauce or sprinkle crushed Oreos on top.
Cover with plastic wrap and refrigerate for at least 6 hours, or overnight for best results.
Slice and serve cold. Store covered in the refrigerator for up to 5 days.