Crush the Oreo cookies into fine crumbs.
In a bowl, combine the crushed Oreos with melted butter to form a crust.
Press the Oreo mixture into the bottom of a springform pan.
Soften the vanilla ice cream slightly and spread it over the crust.
Freeze for 1 hour until firm.
Spread the softened chocolate ice cream over the vanilla layer.
Freeze again for 1 hour to set the chocolate layer.
Top with whipped cream, smoothing it out evenly.
Drizzle chocolate syrup over the whipped cream.
Decorate with additional Oreo cookies, then freeze for at least 2 more hours.