Preheat oven to 350 degrees.

Line a 9×13 pan with heavy duty foil with 4 inches overhang off the sides, creating a sling to lift the bars out when they are finished. Don’t use parchment, the sides will burn under the broiler. Spray the foil with non-stick cooking spray.

In a food processor, grind the graham crackers into crumbs. Pour the crumbs into a large bowl and add the salt and melted butter. Mix together until it resembles wet sand. Add the egg and mix well. Set aside 1/2 cup of the crumb mixture.

Press the crumb mixture into the prepared pan. Bake for 15 minutes or until golden brown. Let the crust cool for a bit while you melt the chocolate.

Melt the chocolate chips using a double boiler on the stove or microwave for 2 minutes at medium power, stirring until completely melted.

Preheat the broiler.

Spread the melted chocolate chips evenly onto the crust. Sprinkle the marshmallows onto the chocolate pressing them in a bit. Sprinkle the reserved crumbs onto the marshmallows, getting the crumbs in the spaces around the marshmallows.

Place pan 6 inches under the broiler for 1-2 minutes until the marshmallows are golden brown.

Refrigerate until the chocolate hardens slightly, about an hour. Remove the bars by lifting the foil sling, cut into squares. Serve cold or at room temperature.