Place the chocolate sandwich cookies in a large zip-top bag and crush them into fine crumbs using a rolling pin or your hands. Set aside about 1/4 cup of crumbs for topping; the rest will be mixed into the layers.
In a mixing bowl, whip the heavy cream with sugar and vanilla using an electric mixer until soft peaks form—this should take about 3-4 minutes. The whipped cream will look fluffy and hold a gentle peak when lifted.
In a separate bowl, whisk together the instant pudding mix and milk until the mixture is smooth and slightly thickened, about 2 minutes. Let it sit for a minute to fully set.
Fold the whipped cream gently into the pudding mixture, creating a light, mousse-like filling. Be careful not to deflate the whipped cream; fold until just combined.
Spread a thin layer of cookie crumbs at the bottom of your baking dish to form the first layer. Then, pour half of the pudding mixture over the crumbs and smooth it out with a spatula.
Add a handful of gummy worms on top of the pudding layer, pressing some in slightly so they peek out for a fun surprise.
Repeat with another layer of cookie crumbs, then the remaining pudding mixture, smoothing the top evenly.
Sprinkle the reserved cookie crumbs over the top layer to resemble fresh earth. Insert more gummy worms to decorate the surface, pressing some into the crumb topping.
Chill the cake in the refrigerator for at least 2 hours to set everything firmly and allow flavors to meld.
Serve chilled, using a big spoon to scoop out messy, layered pieces that showcase the creamy, crumbly, and chewy textures. Enjoy the playful, earthy look!
