OREO Crust: Combine OREO Pieces and butter; press onto bottoms of 2 parchment paper-lined half-sheet pans. Set aside.
Cookie Layer: Cook chocolate squares and butter in double boiler over simmering water until chocolates are completely melted, stirring frequently. Remove top part of double boiler from heat; cool chocolate to 115ºF to 120ºF.
Spoon cheesecake batter into pastry bag fitted with 1/4-inch-round tip; set aside. Beat sugar, eggs, corn syrup and vanilla with mixer fitted with paddle attachment on high speed until thick and lemon colored. Add chocolate; mix well. Gradually add combined dry ingredients, beating after each addition until well blended; pour over OREO Crusts.
Insert tip of filled pastry bag just below surface of chocolate batter in pan; pipe half the batter, in swirling motion, into chocolate batter.
Bake in 325ºF standard oven 18 to 22 min. or until fillings are almost set in centers. Cool completely before cutting to serve.