Preheat the oven to 350°F. In a medium bowl, mix together the graham cracker crumbs, melted butter, and sugar using a fork, then press the crumb mixture into the bottom of a 13×9-inch rectangular greased baking dish. Bake for 7 minutes, then remove from oven and allow to cool slightly.
2 1/4 cups graham crackers, 2/3 cup salted butter, 1/3 cup granulated sugar
Meanwhile, cream the butter and sugars together. Add in eggs and vanilla and beat well until light and creamy. Stir in flour, salt and baking soda just until combined. Then mix in the chocolate chips and 2 cups of the marshmallows by hand.
1 cup salted butter, 3/4 cup granulated sugar, 3/4 cup packed brown sugar, 2 large eggs, 1 teaspoon vanilla, 2 1/4 cups all-purpose flour, 1 teaspoon salt, 1 teaspoon baking soda, 3 cups miniature marshmallows, 1 cup semi-sweet chocolate chips
Carefully spread cookie mixture over the graham cracker crust by dropping spoonfuls of batter evenly around the dish and then gently pressing it together so you aren't disturbing the graham cracker crust beneath.
Bake for 18 minutes at 350°F, then quickly remove from the oven, top with broken pieces of Hershey Bars and sprinkle with remaining 1 cup marshmallows. Return to oven to finish baking. Bake 9-11 minutes more, until golden brown on top. The center should be mostly set but still just a little undercooked. Don't overcook - you want to eat these just a little on a the gooey side, trust me.
3 Hershey bars
Remove and allow to cool completely before cutting and serving.