Preheat your oven to 350°F. Line a muffin pan with cupcake liners or grease with butter and flour.

In a large bowl, sift together the flour, cocoa powder, baking soda, baking powder, and salt.

In another bowl, mix the oil, coffee, vinegar, vanilla, and sugar.

Pour the wet ingredients into the dry ingredients and whisk until just combined.

Divide the batter evenly among the cupcake liners. Bake for 15-20 minutes, or until a toothpick inserted into the center comes out clean.

Let the cupcakes cool completely.

Chop the milk chocolate finely and place it in a heatproof bowl.

Heat the cream until it just begins to boil, then pour it over the chocolate. Let it sit for a few seconds.

Whisk until smooth and glossy. Let it cool to room temperature before using.

In a mixer, cream the butter on medium-high speed until smooth.

Add the cooled ganache and mix until combined.

Add the sifted powdered sugar, cocoa powder, and vanilla. Mix on low until incorporated, then whip on high for about 1 minute.

Combine the egg whites, sugar, cream of tartar, and salt in a heatproof bowl.

Place the bowl over a pot of simmering water, making sure the bottom doesn’t touch the water.

Whisk constantly until the mixture reaches 140°F.

Remove from heat and whip with an electric mixer on high speed until stiff peaks form, about 3-5 minutes. Add the vanilla and mix in.

Use a small spoon to remove the centers of the cupcakes.

Fill the cupcakes with the cooled ganache.

Pipe the chocolate buttercream on top of each cupcake.

Sprinkle the sides with graham cracker crumbs.

Pipe the marshmallow frosting on top of each cupcake. Optionally, use a torch to lightly toast the marshmallow frosting.

Store the S’mores Cupcakes in the fridge for 4 to 5 days.