Preheat oven to 350 degrees F. In a large bowl, combine graham cracker crumbs, flour, baking soda and salt. Set aside.
In another bowl, beat the butter and both sugars until creamy. Add the egg and vanilla, mixing until combined. Slowly add the dry ingredients (mixing on low) until just combined.
Drop by tablespoons of dough into greased mini muffin tin. Press dough down into a muffin tin with a spoon or your thumb creating a well in the center.
Bake for 6-8 minutes or until edges are becoming golden brown.
Remove from oven and place marshmallows in each well, sticky part down. Let cool completely.
Once all cookies are completely cooled, turn on broiler.
Place cookies back in the oven keeping a close eye on them so they don't burn. 1-2 minutes should be fine until they're nice a toasty. Once marshmallows are golden brown, remove from the oven and place a piece of chocolate on each of them.