*About 6 full sheets store-bought crackers.
Preheat oven to 350°F. Line a 12-cup muffin tin with paper liners.
MAKE THE CRUST: Place graham crackers, sugar, and salt in the bowl of a food processor. Grind until fine. With the processor running, pour in the melted butter and mix until the crumbs are evenly moistened, resembling wet sand. Divide the crumb mixture evenly among the muffin tins, about 1 ½ tablespoons per well. Using your fingertips, firmly press each portion of crumb mixture, compacting it into an even layer. Bake until crusts are firm and slightly golden, about 7 minutes. Cool in tins on a wire rack; leave the oven on.
MAKE THE CAKES: Sift together the cocoa, flour, sugar, baking soda, baking powder, and salt in the bowl of an electric mixer. In a medium bowl, whisk together the egg, coffee, buttermilk, oil, and vanilla. Starting with the mixer on low speed, mix the dry ingredients for 30 seconds; slowly pour in the wet ingredients. Increase the speed to medium and beat for 2 minutes. Divide the batter evenly among the muffin tins, pouring it on top of the baked crusts; the cups should be no more than three-quarters full. Bake until the tops of the cupcakes spring back when touched lightly, 22 to 25 minutes. Set on a wire rack to cool.
Notes: This chocolate cake is the sort that will have everyone asking you for the recipe. The combination of coffee and buttermilk gives spectacular depth and richness to the chocolate flavor, and the texture is divinedense, tender, and moist all at once.
WHISK TOGETHER the gelatin and cold water. Let soften for 5 minutes.
PLACE THE EGG WHITES and cream of tartar in the bowl of an electric mixer fitted with the whisk attachment. Beat on high speed until soft peaks form, 2 to 3 minutes. Stop the mixer.
STIR TOGETHER the sugar, corn syrup, water, and salt in a medium saucepan over high heat. Boil, stirring occasionally, until the temperature reaches 230°F.
WHEN THE SYRUP reaches 230°F, quickly whisk in the gelatin. Set the mixer to medium speed and carefully drizzle a few tablespoons of syrup into the egg whites to warm them and avoid scrambling them. Repeat 2 or 3 more times with a few more drizzles and then pour in the rest of the syrup. Beat on high speed until the frosting is tripled in size, 7 to 8 minutes. Beat in the vanilla extract.
Load the icing into a pastry bag fitted with a large tip. Pipe generous swirls of frosting on each cupcake or dollop it on with a spatula. Toast lightly with a kitchen torch. Alternatively, you can place small batches of cupcakes on a baking sheet and pop them under a broiler, watching closely to prevent burning and melting.
Notes: These cupcakes are best eaten the day they are made. If necessary, you can bake the cakes a day ahead and then make, pipe, and toast the frosting the day youre going to serve them.
