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

In a medium bowl, cream together the softened butter and cream cheese until smooth.

Beat in the powdered sugar and vanilla extract until light and fluffy.

In a separate bowl, whip the cold heavy cream until stiff peaks form. Gently fold the whipped cream into the cream cheese mixture.

In another bowl, prepare the chocolate pudding according to package directions using the cold milk.

Layer the crushed cookies, cream cheese frosting, and chocolate pudding in a 9x13 inch baking dish, starting with a layer of cookies. Repeat layers until the dish is full, ending with a layer of cookies.

Decorate with gummy worms, plastic spiders, and chocolate shavings (optional). Refrigerate for at least 2 hours before serving.