Preheat oven to 350 F. In a medium bowl, combine crushed graham crackers with melted butter.
Press mixture into an 8-inch greased baking dish. In a medium bowl, whisk together flour, salt and baking soda. In a large bowl with a mixer, beat softened butter with both sugars until fluffy.
Add in egg and vanilla extract, beat until smooth. Add in flour mixture, beating until all of the flour is incorporated. Fold in the chocolate chips and marshmallows. Press cookie dough over the graham cracker crust.
Bake for 25-30 minutes. Let cool completely, cut into bars.
