Preheat your oven to 350°F (175°C) and line a 12-cup muffin tin with paper liners. In a large bowl, whisk together flour, cocoa powder, sugar, baking soda, baking powder, and salt until well combined.

In a separate bowl, beat eggs lightly, then add buttermilk, cooled coffee, oil, and vanilla extract. Whisk until smooth and well incorporated.

Pour the wet ingredients into the dry ingredients and mix until just combined. Divide batter evenly among muffin cups, filling each about ⅔ full. Bake for 18-20 minutes or until a toothpick inserted in the center comes out clean.

While cupcakes cool completely, reduce oven temperature to 200°F (95°C). In a clean, grease-free bowl, whip egg whites with cream of tartar until soft peaks form. Gradually add sugar, one tablespoon at a time, beating until stiff, glossy peaks form.

Transfer meringue to a piping bag fitted with a large round tip. Pipe ghost shapes onto parchment-lined baking sheets.

Bake meringues for 1 hour 30 minutes, then turn off the oven and let them cool completely inside with the door slightly ajar.

Once both components are completely cool, carefully place one meringue ghost on top of each cupcake. Gently press two mini chocolate chips into each ghost for eyes.