Crush Oreos in food processor and add melted butter and sugar.
Press mixture into bottom and partway up sides of springform pan.
Refrigerate at least 30 minutes to firm.
Beat cream cheese and sugar until well mixed. Set aside.
Whip heavy cream and powder sugar until stiff peaks form.
Fold and blend cream cheese mixture into whipped cream mixture.
Fold chopped Oreos into filling mixture.
Pour/spread into pan.
Refrigerate for at least 4 hours or until firm.
You can also garnish with crushed cookies if desired.