Preheat the oven to 350°F.

Crush the graham crackers into fine crumbs using a food processor or by placing them in a ziplock bag and crushing with a rolling pin.

Mix the crumbs with the melted butter and sugar until well combined.

Scoop about 2 tablespoons of the mixture into each lined cupcake cup, pressing down to form an even layer.

Bake for 8 minutes, then set aside to cool.

In a bowl, whisk together the sugar, flour, cocoa powder, baking soda, baking powder, and salt until evenly combined.

Add the egg, vanilla, buttermilk, and oil. Mix until combined.

Stir in the hot coffee quickly to ensure even distribution. The batter will be thin.

Pour the batter over the baked crust, filling each cup about two-thirds full.

Bake at 350°F for about 20 minutes, or until a toothpick inserted into the center comes out clean.

Place the chocolate, butter, salt, and vanilla in a bowl.

Heat the cream and sugar in a small pan over medium heat until hot but not boiling.

Pour the hot cream mixture over the chocolate and stir until smooth.

Refrigerate until cool but not hard, about the consistency of frosting.

Transfer the ganache to a piping bag with a ¼-inch metal tip, or use a ziplock bag with a ¼-inch hole cut in the corner.

Set up a double boiler: fill a pan with about 1 inch of water and place a heatproof bowl on top, making sure it doesn’t touch the water.

Combine the egg whites, sugar, and cream of tartar in the bowl. Place the bowl over the simmering water.

Heat on low, stirring constantly, until the sugar is dissolved and the mixture is warm. Be careful not to cook the egg whites.

Once the sugar is dissolved, remove from heat and whip on high speed until stiff peaks form and the mixture is glossy. Add the vanilla and mix to combine.

Transfer to a piping bag with a tip, or use a ziplock bag with a ½-inch hole cut in the corner.

Poke a hole in the center of each cupcake and pipe in the ganache filling.

Pipe the marshmallow frosting on top of each cupcake.

Toast the frosting using a kitchen torch for a true s’mores look and taste. If you don’t have a torch, place the cupcakes under the broiler in the oven for 1-2 minutes until golden brown on top.