Preheat oven to 350F. Line a13x9-inch pan with foil, with ends of foil extending over sides.

Mix with the graham cracker crumbs, butter and 3 tablespoons sugar together until all the crumbs are moistened; press onto bottom of prepared pan.

In the bowl of a mixer fitted with a paddle attachment, beat together cream cheese, 1 cup sugar and vanilla in large bowl until smooth. Sift in flour; mix well. Add eggs, 1 at a time, mixing on low speed after each just until blended. Stir chocolate chips into cream cheese mixture with a rubber spatula. Pour over crust.

Bake 30 minutes; remove from oven and sprinkle with Hershey's chocolate bar, mini marshmallows, and chopped graham crackers. The top of the cheesecake will be almost set - don't be afraid to press the toppings down into it slightly. Bake for another 10 minutes or until center is almost set. Cool completely. Refrigerate at least 4 hours. Use foil handles to lift cheesecake from pan before cutting into bars.