Whisk together the flour, graham cracker crumbs, baking soda and salt in a medium bowl. Set aside.
Cream the butter, brown sugar and granulated sugar in a stand mixer until light and fluffy (about 2-3 minutes). Scrape the sides of the bowl to make sure all ingredients are blended.
Add in the eggs and vanilla and beat until combined.
Add in flour, graham cracker, baking soda, and salt mixture. Mix until all combined.
Scoop out dough balls of about 1 TBSP of dough and place on a plate lined with wax paper or parchment paper. Chill for 1 hour. If you are in a hurry, pop the dough balls in the freezer for 30 minutes.
Preheat oven to 350 degrees.
When dough is properly chilled, bake at 350 degrees for 8-9 minutes.
Remove the cookies from the oven and place 3-5 mini marshmallows on the top of each cookie. Return cookies to oven for additional 2-3 minutes.
Remove cookies from oven and cool cookies on cookie sheet for 10 minutes before removing to cooling rack.