Instructions

• Preheat oven to 350°F. Line standard muffin cups with paper liners or grease and flour the cups. (This recipe makes about 18–20 cupcakes.)
• In a bowl, place ¾ cup natural cocoa powder. Slowly whisk in ⅔ cup boiling water until smooth. Let the mixture cool slightly, then whisk in 1 cup buttermilk. Set aside.
• In a separate bowl, whisk together 1¾ cups all-purpose flour, 1½ teaspoons baking soda, and ½ teaspoon salt.
• In the bowl of a stand mixer fitted with the paddle attachment, beat ¾ cup unsalted butter (1½ sticks), 1 cup sugar, and ½ cup brown sugar on medium speed until combined and fluffy.
• Add 3 large eggs one at a time, beating well after each addition. Add 2 teaspoons vanilla extract with the final egg and mix until incorporated.
• Reduce mixer speed to low. Add the flour mixture in three additions, alternating with the cocoa-buttermilk mixture in two additions, beginning and ending with the flour mixture. Beat only until just combined after each addition.
• Divide the batter among the prepared muffin cups, filling each about three-quarters full.
• Bake until the cupcakes are puffed, slightly springy to the touch, and a toothpick inserted into the center comes out clean, about 20 minutes. Remove from oven.
• Let the cupcakes cool slightly in the pan, then transfer them to wire racks and cool completely.
• Prepare the marshmallow filling: In the mixer bowl, beat 6 tablespoons unsalted butter (room temperature) with 1½ cups confectioners' sugar on medium speed until lightened. Add 1 cup marshmallow creme ("fluff"), 1 teaspoon pure vanilla extract, and 2 tablespoons heavy cream; beat until the filling is light and fluffy. Set aside.
• Using a small sharp knife, cut a 1½-inch diameter round hole about 1 inch deep in the center of each cooled cupcake. Reserve or discard the removed cake pieces.
• Fill each cupcake cavity with the marshmallow filling (use a spoon or a piping bag).
• Make the chocolate cream cheese frosting: In a large bowl, beat 8 oz cream cheese (room temperature), ½ cup unsalted butter (1 stick, room temperature), and 2 teaspoons vanilla extract until light and fluffy. Beat in ½ cup unsweetened cocoa powder until combined.
• Gradually add 3 to 4 cups confectioners' sugar, beating until the frosting reaches a spreadable or pipeable consistency.
• Frost the filled cupcakes using an offset spatula or a pastry bag. Sprinkle with gold cupcake gems, if using.