Place the chocolate sandwich cookies in a resealable plastic bag and crush them into fine crumbs using a rolling pin or the bottom of a glass. Set aside.
In a large mixing bowl, whisk together the instant pudding mix and milk until the pudding is thick and smooth, about 2-3 minutes. The mixture should be glossy and start to set.
Gently fold the thawed whipped topping into the pudding mixture until fully combined and fluffy. This helps create a light yet creamy consistency.
Spread a layer of crushed cookies evenly over the bottom of your serving dish or cake pan. This forms the 'dirt' base.
Pour half of the pudding mixture over the cookie crumbs, spreading it out smoothly with a spatula. The pudding will be thick and glossy.
Sprinkle another layer of crushed cookies on top of the pudding, mimicking soil layers.
Repeat with the remaining pudding and cookie crumbs, creating multiple dirt and pudding layers for texture.
Gently press the gummy worms into the top layer of the cake, arranging them to look like crawling through the dirt. Sink some into the pudding for a more natural effect.
Cover the dish with plastic wrap and refrigerate for at least 4 hours, or until the pudding is set and the flavors meld. This chill also helps keep the gummy worms in place.
Once chilled, remove from the refrigerator and serve chilled. The cake should have a crumbly, moist look with playful gummy worms crawling through the 'dirt.' Enjoy the whimsical Halloween treat!
