Line inside of a six inch cake pan with foil and grease. If you are using a six inch springform you don’t need the foil.
Mix together crushed cookies and butter and press into the bottom and slightly up the sides of the pan.
Beat together the softened cream cheese and Nutella. Fold in the whipped topping. Spread over the Oreo Crust. Refrigerate for about 4 hours.
When filling is set, lift from pan and carefully peel away the foil. If you've used a springform, you can just remove the side. Put the cake on some kind of serving plate and keep cold while you make the topping.
With an electric mixer, beat the cream until soft peaks start to form. Gradually add the sugar and add the vanilla. When peaks are stiff, spread or pipe over the hazel mixture. Sift cocoa powder over top and garnish with mini chocolate chips or a cherry or whatever you like. Chocolate syrup is a nice touch too!
If you don’t feel like whipping cream and you like Cool Whip, you can spread or pipe Cool whip over the top instead of making the whipped cream topping