Preheat the oven to 350°F.

Line two cupcake tins with paper liners.

Use a food processor to pulse the graham crackers into crumbs.

Pour in the melted butter and add the ¼ cup of sugar.

Continue to pulse until the crackers come together to form coarse crumbs.

Spoon 2 tablespoons of the crumbs into the bottom of each cupcake liner.

Press down gently with the back of the spoon to form a solid base.

Bake until the crumb crust is just beginning to turn brown, about 8 to 10 minutes.

Remove from the oven and cool to room temperature.

Whisk together the flour, 2 cups of sugar, cocoa, baking soda, baking powder, and salt in a large bowl.

Pour in the buttermilk, brewed coffee, and vegetable oil.

Whisk to combine.

Whisk in the eggs and vanilla.

Continue to whisk until the batter is completely smooth and shiny.

Pour the batter on top of the cooled graham cracker crusts, filling each liner to about ¾ full.

Bake until a tester inserted into the center of the cupcakes comes out clean, about 22 to 25 minutes.

Cool the cupcakes completely to room temperature.

Place the egg whites, the remaining 2 cups of granulated sugar, and cream of tartar into a bowl sitting over a pot of simmering water to create a double boiler.

Whisk continuously until the sugar dissolves and the eggs are warm, about 5 minutes.

Pour the warmed mixture into the bowl of an electric stand mixer.

Beat the egg whites starting on low speed and gradually increasing to high speed.

Whip until the frosting is beautifully shiny and stiff peaks form, about 5 to 7 minutes.

Reduce the speed and mix in the vanilla extract.

Use an ice cream scoop to dollop a generous, towering mound of frosting onto each cooled cupcake.

Use a kitchen butane torch to gently brown the tips of the frosting to perfectly resemble a roasted campfire marshmallow.