Preheat oven to 350°F. Line 2 cupcake pans (24 wells) with paper liners.

Combine graham cracker crumbs, melted butter, and sugar. Divide mixture between liners and press firmly.

In a stand mixer or large bowl, beat together the cake mix, pudding mix, sour cream, vegetable oil, eggs, vanilla, and warm water for about two minutes on medium speed until well combined.

Using a large cookie scoop, distribute the batter evenly among the 24 cupcake wells, about 3 tablespoons of batter per well.

Bake in the preheated oven for 18-22 minutes or until the tops spring back when lightly touched.

Allow cupcakes to cool inside the pans for about 10 minutes.

Remove cupcakes from pans and allow to cool completely on a wire rack. Once cooled, prepare the marshmallow frosting.

Pipe or spread marshmallow frosting onto the cooled cupcakes.

If desired, use a kitchen torch to lightly brown the marshmallow frosting and top with a milk chocolate square.