Preheat oven to 375 degrees F. Line a baking sheet with parchment paper.

Cookie Dough: In large mixing bowl cream together the butter, granulated sugar and brown sugar for 2-3 minutes. Add egg, egg yolk and vanilla then mix. Add flour, graham cracker crumbs, baking soda and salt then mix until combined. Stir in chocolate chips.

Chill dough in the refrigerator for 15 minutes.

Scoop cookie dough into 2 Tablespoon size balls and place on prepared baking sheet, a few inches apart. Press down slightly on the cookie dough balls, to flatten a little.

Bake for 8 minutes. Remove from oven and gently press 2-3 small pieces of Hershey's chocolate and 2-3 mini marshmallows on the top of each cookie. Return to oven for 3-5 minutes.

Allow to cool on the baking sheet for 5 minutes before moving to a wire rack to cool completely.