Preheat the oven to 180°C (356°F).
Mix butter and sugar until smooth and creamy.
Add the egg and vanilla extract, and mix well.
Add flour, baking soda, and salt, then knead the dough.
Fold in chocolate chips and crushed graham crackers.
Shape the dough into balls and place on a baking pan.
Top each dough ball with a marshmallow.
Bake in the oven at 180°C (356°F) for 10–12 minutes.