Preheat oven to 375 degrees F. Line a cookie sheet with parchment paper; set aside. In a large mixing bowl beat butter and shortening with an electric mixer on medium to high speed for 30 seconds. Add brown sugar, granulated sugar, baking soda, and salt. Beat until combined, scraping sides of bowl occasionally. Beat in eggs and vanilla until combined. Beat in as much of the flour as you can with the mixer. Using a wooden spoon, stir in any remaining flour, the marshmallows, chocolate, and crushed graham crackers.
Drop dough by rounded teaspoons 2 inches apart onto the prepared cookie sheet (or use a small to medium cookie scoop to drop dough). Bake for 8 to 9 minutes or until lightly browned. Cool on cookie sheet for 2 minutes. Transfer cookies to a wire rack; cool.