Philadelphia double chocolate cheesecake

24 oreo's crushed.
1/4 cup butter or margarine, softened
4 pkgs 8 oz each softened ream cheese
1 cup sugar
2 T flour
1 tsp vanilla
1 pkg semi sweet chocolate, melted, cooled
4 eggs

Heat oven to 325. Mix crumbs & butter. Press onto bottom of 13x9 lined with foil pan. Bake 10 minutes. Beat cream cheese, sugar, flour and vanilla with mixer until blended. Add chocolate, mix well. Add eggs, 1 at a time mixing on low after each just until blended. Pour over crust. Bake at 45 minutes or until center is almost set. Cool. Refrigerate 4 hours. Use foil to lift cheesecake from pan.