Combine the chocolate pudding mix with cold milk in a mixing bowl and whisk vigorously until the mixture thickens and becomes smooth, about 2-3 minutes.
Place the cookies in a food processor or insert them into a zip-top bag and crush them into fine crumbs using a rolling pin or the back of a spoon.
Spoon a layer of crushed cookies into the bottom of a large serving dish or individual cups, creating a crumbly bed resembling dirt.
Pour the prepared chocolate pudding over the cookie layer, spreading it evenly to create a smooth, dark surface.
Add another layer of crushed cookies on top of the pudding to build up a layered, muddy landscape effect.
Decorate the top with gummy worms, inserting them partially into the pudding and cookie layers to resemble creepy crawlies emerging from the dirt.
Chill the cake in the refrigerator for at least 1 hour to allow the layers to set and the flavors to meld.
Once chilled, serve the Dirt Cake in slices or individual cups, with gummy worms visibly crawling through the layers for a fun Halloween presentation.
