In two bowls, separate the Oreo cookies from its creamy filling and add only the cookies (wihtout the filling) into a food processor. Crush them into crumbs.
Then add the butter and blend or process until well combined.
Transfer to a 20cm cake tin with removable bottom, use a spoon to squeeze and compact the cookie mixture in the bottom of the tin until flat, then take it to the fridge for at least 20 minutes.
In a mixer, add the cream cheese, beat until smooth and creamy, add the sugar and the creamy filling we've separated from the cookies. Beat it all together until smooth and creamy. Microwave the gelatin powder with the water for 20 seconds and add it to the cream. Beat again. Set aside.
Whip the whipped cream mix until it starts to get firm. Don't let it get too firm though. Add this whipped cream to the cream we've set aside and mix it all together until fully combined.
Take the cake tin out of the fridge and add half of the cream, spread well, add 8 Oreo cookies and cover them with the other half of cream. Spread it out evenly.
Process or crush in the blender 12 cookies without the filling to decorate. Spread these cookie crumbs all over the pie. Spread well and take to the fridge for 4 hours. Serve.