In a microwave-safe bowl, microwave the chocolate at 50% power in 30-second increments, stirring each time until the chocolate is melted. Stir until completely smooth. Place the mixing bowl and whisk attachment in the freezer for 5 to 10 minutes to chill.
Prepare the whipped cream. Pour 1 ¼ cups heavy whipping cream into the chilled bowl and use an electric mixer to beat the heavy cream on medium-high speed until the cream starts to thicken. Slowly add the powdered sugar and continue beating on high speed until stiff peaks form. Set the whipped cream aside.
Beat the softened cream cheese until it’s completely smooth. Scrape down the sides of the bowl as needed. Next add the granulated sugar, cocoa powder and vanilla extract and continue beating until smooth.
Next, add the melted chocolate, beating until it’s completely mixed into the cream cheese.
Finally, slowly fold in the whipped cream until it’s completely smooth. Then stir in the crushed Oreos. Pour the filling into the prepared crust, spreading evenly. Refrigerate for 3-4 hours minimum.