Preheat heat 350 degrees F. Line 2 baking sheets with parchment paper, set aside.
In a large bowl, whisk or sift the flour, graham cracker crumbs, baking soda, cinnamon and salt. Set aside.
In the bowl of a stand mixer, beat together the butter and brown sugar until light and fluffy, about 5 minutes. Stir in the egg and vanilla extract until well combined. Add the flour and stir until mixed through. Then stir in the oats and chocolate chips.
Using a small ice cream scoop, scoop out the dough onto the prepared baking sheets, leaving about 2 inches of space between each. Bake until lightly golden brown, about 10 to 12 minutes. Allow to cool slightly on the baking sheets before transferring to a wire rack to cool completely.
Spread half of the cookies, on the bottom, with Nutella. Working with one marshmallow at a time, pierce with a long wooden skewer and then toast on your stove top or with a kitchen torch. Sandwich together with two cookies. Eat right away and enjoy!