Preheat oven on low broil, moving the oven rack to the second from the top, and place baking sheet on the rack.
In a saucepan, warm the milk over medium heat, 5 minutes, don't overheat.
Add the cocoa powder, sugar, chocolate syrup, and the pinch of salt and whisk until well mixed.
Rub a few marshmallows around the top of the two serving mugs, and then dip them in the graham cracker crumbs until well lined.
Pour the hot chocolate then top with 1/4 cup marshmallow to each of the mugs.
Set the mugs on the baking sheet in the oven and broil until marshmallows are browned, don't let them burn.
Remove from the oven and let cool a bit to be safe for handling.
Optionally, drizzle with chocolate syrup and graham cracker crumbs.