Cream the butter and shortening, then add the sugars and beat for one minute.
Add the eggs and vanilla and beat for another minute.
Combine the dry ingredients (flour, graham crackers, baking soda, salt) in a separate bowl, then combine the wet and dry ingredients, mixing until the flour is just barely streaking through.
Add the chocolate chips and mix.
Refrigerate for at least one hour. Typically, I make the dough a day ahead of time to save some time.
Preheat the oven to 350 degrees.
Roll the dough into 1 inch balls and smash into a disk shape. Place a spoon of marshmallow fluff (see pictures above) and top with another disk. Press together and seal the edges.
Place 2 inches apart on baking sheet and bake for 10-12 minutes.
Let the cookies cool for 5 minutes on baking sheet then transfer to rack to cool completely.