Measure and prep all ingredients.
Line a baking sheet with parchment paper.
In a large mixing bowl, using a mixer, cream together butter, sugar, and brown sugar until light and fluffy--about 3 minutes.
Add eggs and vanilla and continue mixing until blended.
In a separate mixing bowl, whisk together graham cracker crumbs, flour, salt and baking soda.
Add dry mixture slowly to the butter mixture and mix until combined.
Stir in the chocolate chips.
Cover and refrigerate the cookie dough for about 15 minutes before baking.
While chilling the dough, preheat oven to 375℉.
Use a large scoop, and scoop chilled cookie dough balls onto the parchment paper lined baking sheet.
Press down slightly in the middle of each ball with the back of a spoon to flatten each cookie a little.
Bake cookies in preheated oven for 8 minutes.
Remove from oven and add 3 small pieces of Hershey's chocolate and 3 miniature marshmallws to each cookie.
Return cookies to the oven for 3-5 minutes, being careful to watch that marshmallows don't melt.
Remove from the oven and leave the cookies on the cookie sheet for about 10 minutes before adding to a cooling rack.
TIP: If marshmallows melt, simply add more marshmallows where they melted when you remove cookies from the oven.
After cooled, store in an airtight container until ready to serve. A few seconds of warming in the microwave when serving makes them even better.
NOTE: You can make dough ahead and keep dough in an airtight container in the fridge for up to 3 days.