Crush Oreos. You can do this in a food processor, or place in a zip-top bag. If using a bag, press excess air out and seal completely before pounding.
Spread half of the Oreo crumbs in the bottom of a 9x13 dish. If making individual portions place 2 tablespoons of crumbs in each cup.
In a large bowl, beat the cream cheese and butter together until smooth. Add cream cheese and mix well.
In a medium bowl, beat together pudding, milk, and vanilla for 2 minutes.
Add pudding mixture to cream cheese mixture and beat well.
Gently fold whipped topping into cream cheese mixture until well combined.
Spread cream mixture over crumbs. Top with remaining Oreo crumbs and refrigerate for 3 hours, or until set.
Decorate with gummy worms.