Preheat the oven to 350 degrees Fahrenheit and line 2 cupcake tins with cupcake liners.
In a small bowl, mix together the graham cracker crust ingredients. Press approximately 1 tablespoon of the mixture into the bottom of each muffin tin and use the bottom of a cup to press the down into the bottom of each cupcake liner.
Bake for 5 minutes. Then remove and let the crust cool.
For the Cupcakes:
In a medium bowl, whisk together sugar, brown sugar, flour, cocoa powder, baking soda, baking powder and salt.
In a large bowl beat eggs, milk, oil and vanilla extract until well combined.
Add dry ingredients to wet ingredients and mix until well combined and no lumps are left. Scrape down sides of the bowl occasionally.
Add boiling water and slowly beat until combined. Batter will be thin.
Pour the batter into the cupcake tins on top of the graham cracker crusts approximately 2/3 of the way full.
Bake for 12-15 minutes until a toothpick inserted into the center comes out clean.
Remove from the oven and let the cupcakes cool completely on wire racks.
For the Frosting:
Stir together the egg whites, sugar and cream of tartar in a heatproof bowl. Set the bowl over a saucepan with simmering water. Whisk constantly until the sugar is dissolved.
Then transfer the mixture to an electric mixer bowl fitted with the whisk attachment. Beat on low speed and gradually increase to high speed until stiff glossy peaks are formed. Add in the vanilla extract and mix until combined.
Pipe the frosting in a spiral motion on top of each cupcake. Use a kitchen torch to lightly brown the top of the frosting.
Then top with a piece of the graham cracker and chocolate bar.
Notes
Refrigerate the leftovers, covered, for up to 5 days.