Crush your package of Oreos and push 2/3 onto the bottom of a 9x13 pan. Set aside.
In a small mixing bowl, add the pudding mixes and 3 cups milk. Whisk until there;s no more clumps and set aside.
In the bowl of a stand mixer or a large mixing bowl, add the cream cheese and butter. Beat on medium speed until smooth, about 2 minutes. Add in the icing sugar and vanilla and mix until combined.
Mix in pudding mixture until combined. Add the cool whip and gently fold it in with a spatula.
Spread this mixture gently over top of the pressed down Oreo crumbs. Get it as flat as you can. Then spread the other 1/3 of your Oreo crumbs on top. Place in the fridge to chill for at least 4 hours.
While it chills, make you decorations. If you'd like to make the ghosts I've made, spread some parchment paper on top of a cookie tray. Then melt your white chocolate in a glass that you can dip into.
Dip the top 2/3 of a Milano cookie and set it on the parchment paper. Immediately place 2 eyes next to each other on the top. Repeat this until you have as many ghosts as you want.
Once the white chocolate has set a little, with black gel icing or melted chocolate, draw a little oval mouth under the eyes. Place your ghosts in the fridge to fully set.
Once your cake has chilled for 4 hours, place your decorations on top how you like and serve! Store in the fridge for up to 5 days and enjoy!