01 -
Set the oven to 350°F. Heat the butter in the microwave for about 40 seconds until it's fully liquid.
02 -
Blend the softened butter with both types of sugar until smooth. Add the egg and vanilla, stirring until combined.
03 -
Stir in the flour, salt, and baking soda gently until the dough just comes together. It should feel soft, not sticky.
04 -
Mix in the marshmallows, chocolate chips, and graham cracker crumbs, folding them into the dough.
05 -
Scoop about 3 tablespoons of dough per cookie onto the baking sheet, spaced 2 inches apart. Bake for 10-15 minutes until puffy and set.