Prepare the chocolate pudding. In a large mixing bowl, whisk together the instant chocolate pudding mix and cold milk for approximately 2 minutes, until the pudding begins to thicken. Refrigerate for 5 minutes to allow the pudding to set.

Fold in the Cool Whip. Gently fold the thawed Cool Whip into the chocolate pudding until completely combined. The mixture should be smooth, creamy, and fluffy. Refrigerate while preparing the topping.

Make the crunchy dirt topping. Place the Oreo cookies in a food processor and pulse until crushed, leaving a combination of fine crumbs and small cookie pieces. Place the cornflakes in a zip-top bag and lightly crush them with your hands or a rolling pin, leaving some larger pieces for extra crunch. Combine the crushed Oreos and cornflakes in a bowl and toss until evenly mixed.

Assemble the dirt cake cups. Spoon a small layer of Oreo-cornflake crumbs into the bottom of each individual dessert cup. Add a generous layer of chocolate pudding filling, then repeat with another layer of crumbs and pudding until the cups are nearly full. Cover and refrigerate for at least 2 hours.

Decorate and serve. Just before serving, sprinkle a generous layer of the crunchy Oreo-cornflake topping over each cup. Tuck a gummy worm into the top of each dessert and serve with a small spoon.