For the graham cracker crust: Preheat the oven to 350 degrees F. Line two standard 12-cup muffin tins with paper liners.

In a small bowl, stir together the graham cracker crumbs, butter and sugar until well combined. Press a heaping tablespoon of the crust mixture into the bottom of each muffin cup and bake until golden and just set, 5 to 7 minutes. Set aside to cool.

For the cupcakes: In a large bowl mix together ingredients on your box directions. Divide the batter among the muffin cups, filling them about two-thirds full. Bake until a toothpick inserted into the center comes out with a few crumbs attached, 12 to 15 minutes.

Let cool in the tins on a wire rack for about 5 minutes, then remove the cupcakes from the tins and allow to cool completely.

For the marshmallow frosting: Combine the egg whites, sugar and cream of tartar in a heatproof mixing bowl set over a pan of simmering water. Whisk constantly until the sugar has dissolved and the egg whites are warm and smooth to the touch, 3 to 5 minutes. Transfer to the bowl of a stand mixer fitted with the whisk attachment and beat on low speed, gradually increasing to medium and then finally up to high. Beat until stiff, glossy peaks form, 7 to 10 minutes. Turn the mixer to low and whisk in the vanilla.

Spread the frosting on the cupcakes. With a handheld pastry torch, lightly brown the frosting (I don't have a torch so I just skipped this step). Decorate each cupcake with a graham cracker piece and a piece of chocolate.