Preheat oven to 350 F and line cupcake tins with cupcake liners.
In a small bowl, mix together graham cracker crumbs, 3 T of sugar and 4 T of butter.
Press a scant tablespoon of the graham cracker crumb mixture into the cupcakes liners. The cupcake recipe makes about 20.
Boil 1 cup water in microwave. Whisk in cocoa and vinegar until smooth. Let cool.
Meanwhile, in a stand mixer, beat 1 stick butter for 4 to 5 minutes on high speed. Add the sugar and beat for another couple minutes. Add the oil and eggs, mixing well. Stir in the cocoa mixture.
In a separate bowl, whisk together the flour, salt and baking soda.
Add to the mixer and mix until just combined.
Fill lined cupcake tins about 2/3 full.
Bake at 350 for 12-15 minutes or until they spring back when lightly touched. Cool completely on wire racks.
Using a sharp knife, cut a wedge shaped piece out of the center of each cupcake. Fill with a teaspoon or two of marshmallow fluff. Here is a great tutorial on how to fill cupcakes without fancy equipment.
To make the frosting, beat the butter until smooth.
Beat in 3 cups of powdered sugar until smooth.
Add enough of the milk to reach the right consistency for spreading or piping. Beat in a bit of salt to taste.
Frost the cupcakes and sprinkle with additional graham cracker crumbs if desired.