Carefully separate Oreo cookie and scape off the filling for 8 cookies. Leave in the filling for the other 4 cookies.
Break each cookie in to 6-8 pieces or take the cookies in a Ziploc bag and lightly pound with a heavy object to crumble the cookies.
Take cookies in a food processor or a blender and process for few seconds until it crumbles.
Add rest of the ingredients and process until desired texture and consistency is reached. Start with less water or milk and add more as required.
Transfer to an air tight container and refrigerate. Stays good for at least a week.