Crush cookies in 2 or 3 batches in a food processor. Pulse until you get fine crumbs, about 30 seconds per batch. Transfer to a bowl.
Place cream cheese, butter, and confectioner's sugar in food processor; mix until smooth, about 30 seconds.
Whisk milk and pudding mixes together in a bowl until pudding is thickened; fold in whipped topping. Stir in cream cheese-butter mixture.
Press 1/3 of the cookie crumbs onto the bottom of a 9x13-inch pan. Sprinkle half of the gummy worms on the crumb layer. Spread half of the pudding mixture over the crumbs and candy. Carefully layer another 1/3 of the crumbs over the pudding mixture and sprinkle on more gummy worms. Add the last layer of cookie crumbs and smooth them out for your "pumpkin patch."
Place pumpkin candy in rows with enough room to for frosting "vines" and "leaves."
Tint frosting with green food coloring and transfer to piping bag. Connect pumpkins with "vines" and add swirling tendrils. Switch to a leaf tip and create some leaves.
