Graham Cups

1. Preheat the oven to 325 degrees. Lightly spray a muffin pan with nonstick cooking spray; set aside.
2. Either crush the graham crackers by hand, until they are like rough sand, or process in a food processor for several pulses. Add the sugar and mix, or pulse, to combine. Add the butter and mix until thoroughly combined and resembling wet sand.
3. Press firmly into the cups of the muffin pan, being sure to push it up the sides of the cups. Bake until golden and fragrant, about 10 to 12 minutes. Allow to cool completely before filling.

Cupcakes

1. In a medium bowl, combine the flour, cocoa, baking soda, baking powder, and salt; set aside.
2. In a large bowl, or the bowl of a standing mixer, cream together the butter and sugar until light and fluffy. Add the eggs, one at a time, beating until just combined. Stir in the vanilla.
3. Sprinkle 1/3 of the flour mixture into the mixing bowl and mix until just combined. Add half of the sour cream, mixing until just combined. Repeat, alternating the remaining flour in 2 more additions with the remaining sour cream in one more addition (ending on flour).
4. Place 2 scant tablespoons of batter into each prepared muffin cup. Bake for 15 to 18 minutes, until the tops of the cupcakes spring back lightly when touched.
5. Transfer to a wire cooling rack and allow to cool completely before frosting.

Frosting

1. Combine egg whites, sugar, and cream of tartar in a medium bowl set over a pot filled with a couple of inches of barely simmering water.
2. Whisk the mixture frequently to prevent the egg whites from cooking. Continue whisking lightly until the mixture reaches 160 degrees.
3. Remove the bowl from the heat and whisk the mixture on high until the whites are shiny and hold stiff peaks, about 7 to 8 minutes. Gently stir in vanilla extract.

Milk Chocolate Ganache

1. Place the chocolate in a heatproof bowl; set aside.
2. In a small saucepan set over medium high heat, bring cream to a simmer. Remove from heat and pour over the chocolate. Let stand for 10 minutes, then whisk until smooth. Allow to cool completely before using, whisking occasionally.

Assembling

1. Pipe the frosting onto each of the cupcakes with a large French Star tip. Let the meringue set for 10 minutes. Set the oven's broiler at this time.
2. Working with two cupcakes at a time, place the cupcakes into the oven on broil and let it toast for 20 seconds. Rotate and let it toast for another 20 seconds. If not golden, repeat again. (All ovens are different with toasting times. Use your best judgement!)
3. Place the cupcakes in the refrigerator to firm up for at least 15 minutes. Drizzle on the chocolate ganache and place mini marshmallows.