Preheat oven to 350°F and line a baking sheet with parchment paper.

In a bowl, whisk together the melted butter, brown sugar, and granulated sugar until smooth and combined.

Add the egg and vanilla extract, then whisk until the mixture is glossy and well incorporated.

In a separate bowl, mix the flour, baking soda, and salt.

Add the dry ingredients to the wet ingredients and mix until just combined.

Fold in the chocolate chips.

On the prepared baking sheet, place a graham cracker square as the base.

Top with a few pieces of Hershey’s chocolate and one large marshmallow.

Scoop cookie dough, flatten it in your hand, and wrap it completely around the s’mores filling, sealing the edges well.

Bake for 12–14 minutes, or until the edges are golden and the centers are just set. Baking time may vary depending on cookie size.

Let cool for at least 10 minutes before eating; the marshmallow filling will be extremely hot.