Begin by whisking the instant chocolate pudding mix with cold milk in a mixing bowl until the mixture thickens and is smooth, about 2-3 minutes.
Pour the prepared pudding into a large serving dish or individual cups, spreading it evenly with a spatula.
Sprinkle the crushed cookies evenly over the layer of pudding, creating a dirt-like surface with some crumbs falling over the sides.
Place a few Gummy worms on the surface and partially hiding them in the cookie crumbs to give a spooky, buried effect.
Repeat the layers if desired, adding another layer of pudding and crumbs to create a taller, more layered dirt cake.
Finish by decorating the top with additional Gummy worms, ensuring some appear to be crawling out of the 'dirt.'
Refrigerate the dirt cake for at least 1 hour to allow flavors to meld and the pudding to set completely.
Serve the Halloween Dirt Cake chilled, with gummy worms scattered on top for a fun, creepy presentation.