Created by JostLori on June 8, 2016
Step 1: Make the cupcakes: Heat oven to 350° F with the racks in the middle and top positions. Line a standard 12-cup muffin tin with paper liners.
Step 2: Whisk together the graham cracker crumbs, flour, baking powder, and salt in a medium bowl.
Step 3: Beat the butter and sugar in a separate bowl with an electric mixer on medium-high until light and fluffy, 2 to 3 minutes. Beat in the eggs, one at a time, then the vanilla, scraping down the sides of the bowl as necessary.
Step 4: Reduce mixer speed to low and add the dry ingredients and milk alternately, beginning and ending with the dry ingredients and mixing well between additions. Mix until just combined.
Step 5: Divide the batter among the muffin cups. Bake, on the middle rack, rotating once, until a toothpick inserted in the center of a cupcake comes out clean, 20 to 24 minutes. Cool in the tin for 10 minutes; transfer to a wire rack to cool completely.
Step 6: Make the topping: Place the marshmallows on a parchment-lined baking sheet, 2½ inches apart. Bake on the top rack until golden and deflated, 6 to 10 minutes. Let cool.
Step 7: Make the ganache: Meanwhile, bring the cream to a boil in a small pot. Remove from heat, add the chocolate, and let sit for 5 minutes. Whisk to combine. Let cool slightly.
Step 8: Assemble the cupcakes: Divide the ganache among the cupcakes, then top each with a toasted marshmallow. Let sit until the ganache is almost firm to the touch, 15 to 20 minutes, before serving.