I'm not sure if this could actually be considered a recipe lol, but I did an Oreo filling by just mixing crushed up cookies into regular buttercream. It was actually really good!
There is one in the recipe section. I used it to fill the center of a ch choc cake using the Wilton fanci fil cake pans. Yummy, just don't overwhip the heavy cream like I did--still good, but it peaked and I kept yaking on the phone and ..................then the peaks avalanched! 
1 sm package of cream cheese, cream in mixer, fold in 1/2 cup sugar and one tub (small) of cool whip, crush 12 oreo cookies (or more if you like)up and add. I usually put between layers of Chocolate cake topped with chocolate ganache. Sometimes also top with choco dipped strawberries. My family loves it and everyone always ask for it at all family gatherings. YUMMY.
This one is REALLY good. It's the same as the WBH recipe.
http://www.cakecentral.com/cake_recipe-2079-0-Cookies--Cream-Filling.html
I second the recipe posted by nickshalfpint.
I made it and it was a huge hit!
i mix together 3 oz cream cheese, 1/2 cup butter, 4 cups confectioners sugar, and 1/2 a teaspoon of vanilla extract to make a batch of oreo filling.
I would take either vanilla pudding or white chocolate pudding, and crumble up oreo's into that...yummy!
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