Preheat your oven to 350°F and line a 9x13-inch baking pan with parchment paper
In a large mixing bowl, combine the gluten-free flour, graham cracker crumbs, baking powder, cinnamon, nutmeg, and salt and whisk until well mixed and set aside
In a separate bowl, cream together the softened butter, greek yogurt, and coconut sugar on medium speed with a hand mixer until light and fluffy, about 2-3 minutes
Add the eggs, one at a time, beating well after each addition then mix in the vanilla extract
Gradually add the wet ingredients to the dry ingredients, mixing on low speed until just combined
Spread 3/4 of the dough evenly into the prepared baking pan
Sprinkle marshmallows and chocolate chips on top and then the remainder of the dough
Bake for 25-30 minutes, or until the edges are golden brown and a toothpick inserted into the center comes out mostly clean (some gooey marshmallow bits are fine!)
Let cool completely in the pan before slicing into bars