Bake Brownies according to direction on box.
Break approximately ten whole graham crackers up into small pieces. Sprinkle over the baked brownies.
Sprinkle 4 cups of miniature marshmallows on top of graham crackers.
Broil on High for about 1 minute or until marshmallows are toasted to your liking. It's super fast, so watch carefully. Remove from oven and let cool before cutting.