Preheat your oven according to the instructions on the chocolate cake mix box. Prepare the cake batter according to the package directions, mixing in the required water, oil, and eggs. Pour the batter into a greased 9x13 inch baking dish and bake for 30-35 minutes until a toothpick inserted in the center comes out clean. Allow the cake to cool completely in the pan.
Once the cake has cooled, use a toothpick or skewer to poke holes all over the surface of the cake.
In a mixing bowl, whisk together the two boxes of Oreo pudding mix with the 3 cups of milk until smooth and thickened, about 2 minutes.
Carefully pour the prepared Oreo pudding over the poked cake, ensuring it seeps into the holes. Use a spatula to spread it evenly.
Cover the cake with plastic wrap and refrigerate for at least 4 hours, or overnight if possible.
After chilling, remove the cake from the refrigerator and spread the whipped cream evenly over the top.
Sprinkle the crushed Oreos over the whipped cream layer for garnish.
Slice the cake into squares and serve chilled.