Preheat oven to 350 degrees.

Place graham crackers in a single layer on the bottom of a greased 9×13 pan (I line my pan with foil to easy remove the brownies and cut them into squares). A couple of the graham crackers will need to be cut to fit and cover the bottom of the pan.

Prepare brownie mix according to package directions (I always follow the instructions for cake like), then pour the batter over the graham crackers.

Bake at 350 degrees for 25-30 minutes until a toothpick comes out clean. Remove the pan from the oven and top with the marshmallows and chocolate chips. Return the pan to the oven for 3 more minutes.

Remove from oven and sprinkle with nuts if desired. Cool before cutting into squares. Makes 18-24 brownies.