Process oreo cookies in a food processor until finely ground.
Combine oreo crumbs and melted butter in a medium bowl and stir to mix well. Pour into a 9-inch springform pan. Press into the bottom of the pan. Refrigerate until needed.
In a clean bowl, use electric mixer to beat heavy whipping cream until stiff peaks form. Set aside. (Half will be mixed into the peanut butter layer and half into the chocolate layer.)
In another bowl, beat cream cheese, butter, and peanut butter until smooth.
Beat in confectioners' sugar.
Fold half of the whipped cream into the peanut butter mixture. Spread mixture evenly on top of crust. Stick back in the refrigerator.
Place bittersweet chocolate and milk chocolate in a small bowl.
In a small saucepan, bring sugar and milk to a boil, stirring to dissolve sugar. As soon as mixture comes to a boil, pour it over the chopped chocolate. Whisk until smooth.
Stir vanilla into chocolate mixture. Cool to room temperature, stirring occasionally.
Fold remaining whipped cream into chocolate mixture. Pour on top of peanut butter layer and refrigerate or freeze until firm
To make ganache, place chopped semi-sweet chocolate in a small bowl.
Bring heavy cream to a boil. Pour over chocolate. Stir until smooth. Stir in vanilla. Cool until almost room temperature, stirring occasionally.
Spread over cheesecake. Refrigerate at least 1 hour before serving.