Place the chocolate cookies in a food processor or inside a plastic bag and crush them into fine crumbs using a rolling pin or a heavy object.
In a mixing bowl, whisk together the instant chocolate pudding powder and milk until the pudding begins to thicken, about 2 minutes.
In another bowl, beat the softened cream cheese, powdered sugar, and vanilla extract together until smooth and creamy.
Fold the cream cheese mixture into the pudding until fully combined and smooth.
Gently fold in the whipped topping to lighten the mixture and add air, resulting in a fluffy consistency.
Add half of the crushed cookie crumbs into the mixture and stir until evenly incorporated, creating a chocolatey, dirt-like color.
Pour the mixture into a serving dish or trifle bowl, smoothing the top with a spatula.
Sprinkle the remaining crushed cookie crumbs evenly over the top to resemble soil.
Decorate the surface with gummy worms by burying some into the crumbs and placing others on top to resemble worms underground.
Refrigerate the dirt cake for at least 2 hours or until set, allowing flavors to meld and the texture to firm up.
Serve chilled, with additional gummy worms if desired, for a whimsical Halloween dessert.
