Preheat the oven to 375 degrees.

In a medium bowl whisk together the flour, baking soda, and sea salt. Set aside.

In another medium bowl cream the butter, brown sugar, and sugar. Mix well.

Add the egg and vanilla to the sugar mixture and mix until well combined.

Add the sugar mixture to the flour mixture and mix until combined.

Fold in the chocolate chips and marshmallows.

Place graham cracker squares on baking sheets, making sure they are at least 2 inches apart.

Spoon a large tablespoon of dough on top of each square. Press down on the dough.

Bake for 7 minutes and then remove from the oven. Place a Hershey bar piece on top of the dough and then return to the oven.

Continue to bake for 5-7 minutes or until golden brown.

Remove from oven and let sit for 5 minutes before removing to a cooling rack to cool completely.