In a medium bowl, stir together all of the ingredients for the graham cracker crust until completely combined. Divide the crumbs between the muffin tins, and press the crumbs on the bottom and up the sides of the tins. Set aside while you prepare the brownie batter.
Put the chocolate and butter in a large glass bowl and microwave for 30 seconds. Stir, and repeat until the chocolate and butter are completely melted and smooth. Add the sugars. Whisk until completely combined. The mixture should be room temperature.
Remove brownies from oven and place a marshmallow on top of each brownie. Return to the oven for 1-2 minutes or until marshmallows are light golden brown. Keep a close eye on the marshmallows while they bake.
For the crust
For the brownies