In a mixing bowl, whisk the instant chocolate pudding mix with 2 cups of cold milk until the mixture thickens and is smooth, about 2 minutes. Set aside.
In a separate large bowl, beat the softened cream cheese until creamy and smooth, using a hand or stand mixer on medium speed.
Add the powdered sugar and vanilla extract to the cream cheese, then beat briefly until combined and smooth.
Fold the prepared pudding into the cream cheese mixture using a spatula until fully incorporated and creamy.
Crush the Oreo cookies into coarse crumbs. You can do this by placing them in a sealed plastic bag and gently crushing with a rolling pin or by pulsing in a food processor.
Spread a layer of crushed Oreos at the bottom of your dish or trifle bowl, creating a crumbly base.
Top the Oreo layer with a generous scoop of the chocolate pudding and cream cheese filling, spreading it evenly with a spatula.
Add another layer of crushed Oreos over the pudding layer for added texture and flavor.
Repeat the layering process — pudding mixture and Oreo crumbs — until you've used all ingredients, finishing with a crumb layer on top.
Decorate the top with gummy worms, pushing some lightly into the crumb topping to resemble worms burrowing into the dirt.
Cover the dish and refrigerate for at least 1 hour to allow the flavors to meld and the layers to set.
Serve chilled, with gummy worms visible on top for a festive spooky effect. Enjoy this fun, no-bake Halloween treat!
