Preheat Oven & Prep Pans
Preheat your oven to 350°F (175°C). Line a 12-cup muffin pan with cupcake liners and lightly spray with nonstick cooking spray.

Mix Dry Ingredients
In a medium bowl, sift together the flour, black cocoa powder, salt, baking soda, and baking powder. Set aside.

Bloom the Chocolate & Coffee
In a separate bowl, combine chopped semisweet chocolate and instant coffee. Pour in boiling water and stir until melted and smooth. Let cool slightly.

Combine Wet Ingredients
In a large mixing bowl, whisk together sour cream, vegetable oil, vanilla extract, eggs, and granulated sugar until smooth.

Add Chocolate Mixture
Pour the cooled chocolate/coffee mixture into the wet ingredients. Mix until fully incorporated.

Incorporate Dry Ingredients
Gradually add the dry ingredients to the wet mixture. Stir just until combined—don’t overmix. Batter will be thin.

Bake
Fill each cupcake liner about ⅔ full. Bake for 18–22 minutes or until a toothpick inserted into the center comes out clean. Cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.

Make the Frosting
In a large bowl, beat the butter until creamy. Add confectioners’ sugar a cup at a time, mixing well after each addition. Add salt, milk, and vanilla extract, then beat on high until fluffy and spreadable (about 3–4 minutes).

Frost the Cupcakes
Transfer frosting to a piping bag fitted with a large round tip. Pipe tall swirls to form ghost shapes. Sprinkle with black sanding sugar, then use black gel icing to draw eyes and mouths.

Serve or Store
Serve immediately or refrigerate in an airtight container for up to 3 days. Allow to come to room temperature before serving.