In a mug, add in the butter, graham cracker crumbs, brown and granulated sugar. Stir to combine.
Add in the milk and stir until combined.
Add in the flour, baking powder and ground cinnamon. Stir until combined and smooth.
Stir in the mallow bits and pieces of chocolate. If you can't find mallow bits, mini marshmallows will work as well.
Place in the microwave. Heat for 1 minute and 35 seconds. I have a 900 watt microwave.
Place mini marshmallows on top of cake. Toast with a kitchen torch. Place the candy bar in the side of the cake.
Let cool slightly and eat.