Bake for 15-17 or until toothpick comes out clean. Let cool in muffin tin for 5 minutes and then remove and cool completely on a cooling rack.
For the Ganache:
In a small sauce pan, combine chocolate chips and whipping cream over medium-low heat until melted and smooth. Let it cool for 5 minutes and then spoon onto the center of each cupcake. Let the ganache set up on the cupcake before adding frosting (put in fridge for 5 minutes to speed this up). Place remaining ganache in a piping bag or ziploc baggie.
For the Marshmallow Frosting:
Beat the butter and powdered sugar together until fluffy. Fold in the marshmallow fluff by hand. Place in piping bag fitted with 1A (extra large round) tip or just cut the tip of the bag off. Pipe on frosting.
Drizzle with leftover ganache and sprinkle with crushed graham crackers.