Preheat the oven to 350°F (177°C). Line a 12-count muffin pan with cupcake liners. Line a second pan with 2 liners—this recipe makes about 14 cupcakes. Set aside.

In a large bowl, whisk the cocoa powder, flour, baking soda, baking powder, and salt together until thoroughly combined. Set aside. In a medium bowl, whisk the eggs, sugar, brown sugar, oil, and vanilla together until completely smooth. Pour half of the wet ingredients into the dry ingredients. Then half of the buttermilk. Gently stir—about 5 stirs. Repeat with the remaining wet ingredients and buttermilk. Stir until *just* combined; do not overmix. The batter won’t be very thick.

Pour/spoon the batter into the liners—fill only halfway to avoid spilling over the sides. Bake in batches for 18-19 minutes, or until a toothpick inserted in the center comes out clean. Allow to cool completely before continuing.

In a medium bowl using a handheld or stand mixer fitted with a paddle attachment, beat the butter, marshmallow creme, vanilla, and cream on medium speed until completely smooth. Add 3/4 cup confectioners’ sugar and the salt slowly with the mixer running on low, then increase the speed to high and beat for 1 minute. If it looks too thin, add 1/4 cup more confectioners’ sugar. Refrigerate the filling until ready to use.

Sift together the confectioners’ sugar and cocoa powder to assure there are no lumps. Set aside. With a handheld or stand mixer fitted with a paddle attachment, beat the butter on medium speed until creamy—about 2 minutes. Gradually add the sifted sugar/cocoa powder alternately with the heavy cream and vanilla. Beat on low speed after each addition. Once all added, beat on high speed until creamy and combined for at least 2 minutes. Add a pinch of salt if frosting is too sweet. Set aside until ready to use.

Using a sharp knife, cut a circle/hole into the center of the cupcake to create a little pocket about 3/4 inch deep. Place 1 spoonful (a little more than 1 teaspoon) of marshmallow filling inside and top with the piece of cupcake you removed to seal. See photos above for visual. Repeat with all cupcakes. You will likely have leftover filling. It’s great sandwiched between two chocolate chip cookies.

Frost the cupcakes however you like. I used my Wilton 1M swirl piping tip. Sprinkle with crushed graham crackers.

Toast the marshmallows on a large baking sheet on one of the top oven racks with your oven on broil. They brown almost immediately, so don’t leave the room! Once browned, quickly remove and let cool for 5 minutes. Scoop from the baking sheet using a spatula and place on top of the frosted cupcakes. Enjoy immediately while the marshmallows are nice and gooey.