Make the Cupcakes:

1. Preheat oven to 350°F (175°C). Line two standard 12-cup muffin tins with cupcake liners.

2. In the bowl of a stand mixer, whisk together the flour, sugar, black cocoa, baking soda, baking powder, and salt.

3. Add the eggs, buttermilk, hot coffee, oil, and vanilla to the dry ingredients. Mix on medium speed until the batter is smooth, about 2 minutes. The batter will be thin.

4. Divide the batter evenly among the prepared cupcake liners, filling each about 2/3 full.

5. Bake for 18-22 minutes, or until a toothpick inserted into the center comes out clean.

6. Allow the cupcakes to cool in the pans for 5 minutes before transferring them to a wire rack to cool completely.

Make the Frosting & Decorate:

1. In the clean bowl of a stand mixer fitted with the paddle attachment, beat the softened butter on medium-high speed until light and creamy, about 3 minutes.

2. Add the marshmallow fluff and beat for another 2 minutes until fully combined and fluffy.

3. Gradually add the sifted powdered sugar with the mixer on low, increasing to medium-high once incorporated. Add the vanilla and salt. Beat for 3-4 minutes until extremely light and fluffy.

4. Fit a large piping bag with a large round tip (e.g., Wilton 1A or 2A). Fill the bag with the frosting.

5. To pipe a ghost, start at the base of a cooled cupcake and apply steady pressure, pulling up to form a tall, wobbly mound. Release pressure and pull away to form the top of the ghost’s head.

6. Gently press two mini chocolate chips into the frosting to create eyes.