Preheat your oven to 350°F (175°C).
In a large bowl, cream together the softened butter, brown sugar, and granulated sugar until smooth.
Beat in the egg and vanilla extract until well combined.
In another bowl, whisk together the flour, baking soda, and salt.
Gradually add the dry ingredients to the wet mixture, stirring until just combined.
Fold in the mini marshmallows, chocolate chips, and crushed graham crackers.
Scoop tablespoon-sized portions of dough onto a baking sheet lined with parchment paper.
Bake in the preheated oven for 10-12 minutes or until the edges are golden.
Remove from the oven and let cool on the baking sheet for a few minutes before transferring to a wire rack.