In a large mixing bowl, combine the instant vanilla pudding mix and 2 cups of cold milk. Blend on medium speed for about 2 minutes until smooth and lightly thickened. Add the softened cream cheese and continue mixing until fully incorporated.

Carefully fold in 8 ounces of Cool Whip into the cream mixture using a spatula. Cover the bowl with plastic wrap and refrigerate for 15 to 30 minutes.

Crush 15 to 20 Oreo cookies in a resealable plastic bag using a rolling pin. Set these crumbs aside.

In a trifle bowl or large casserole dish, spoon half of the cream mixture and sprinkle half of the Oreo crumbs. Repeat the layers, finishing with a top layer of Oreo crumbs.

Decorate with gummy worms or seasonal candies just before serving.