Combine Oreo crumbs and melted butter, then press into the bottom of a 9-inch springform pan. Set in fridge.
Beat the cream cheese, sugar, and vanilla until smooth. Add cocoa powder and melted chocolate; mix well.
In a separate bowl, whip the heavy cream and powdered sugar until stiff peaks form.
Fold the whipped cream into the chocolate mixture in two parts until well combined.
Spread the filling evenly over the crust. Refrigerate for 5β6 hours or overnight.
Before serving, remove from pan and top with chocolate whipped cream and chocolate shavings if desired.