Preparation / Directions:
FOR CRUST: COMBINE graham cracker crumbs, butter and sugar in medium bowl; press onto bottom of ungreased 13 x 9-inch baking pan. FOR FILLING: BEAT cream cheese, sugar and flour in large mixer bowl until smooth. Gradually beat in evaporated milk, eggs and vanilla extract.
MICROWAVE morsels in medium, microwave-safe bowl on HIGH (100%) power for 1 minute; stir. Microwave at additional 10- to 20-second intervals, stirring until smooth. Stir 1 cup cream cheese mixture into chocolate. Pour remaining cream cheese mixture over crust. Pour chocolate mixture over cream cheese mixture. Swirl mixtures with spoon, pulling plain cream cheese mixture up to surface.
BAKE in preheated 325ø F. oven for 40 to 45 minutes or until set. Cool in pan on wire rack to room temperature; chill until firm. Cut into 15 rectangles; cut each rectangle in half diagonally to form triangles.