Crush chocolate sandwich cookies into fine crumbs. You can do this in a food processor or by placing them in a ziplock bag and crushing with a rolling pin.

In a large bowl, combine crushed cookies, cocoa powder, milk, and vegetable oil. Mix until a moist, crumbly mixture forms. This is your 'dirt'.

In a separate bowl, whisk together the chocolate pudding mix and cold milk until smooth and creamy. Let it stand for 5 minutes to slightly thicken.

Layer the pudding and 'dirt' mixture in individual serving glasses or a trifle bowl. Start with a layer of pudding, then a layer of 'dirt', repeating until you finish with a layer of 'dirt'.

Gently press gummy worms into the top layer of 'dirt'.

If using, sprinkle crushed green cookies around the edges of the glasses or bowl to resemble grass.

Refrigerate for at least 30 minutes to allow the pudding to set completely before serving.