1. Preheat oven to 350F. Line a baking sheet with parchment paper. Whisk together flour, sugar, baking powder, and salt in a large bowl. Mix vanilla extract, egg, and buttermilk until well-combined in another medium bowl.

2. Add buttermilk mixture to the dry ingredients and stir until there are no flour streaks left. Pour in all the melted butter at once. Stir until well combined.

3. Using a tablespoonful, transfer some batter onto the prepared baking sheet (you should have 24-26 individual cookies). Bake for 12-15 minutes until cookies are set and spring back when lightly pressed. Leave the cookies to cool on the baking sheet for 3-4 minutes, and then transfer them to a wire rack to cool completely before decorating.

4. Finally, make the filling. Whip all ingredients in a large bowl until frosting is thick and smooth. Frosting shouldn’t be too thick so add an extra teaspoon of milk to lighten. On the other hand, if frosting is too thin, add extra confectioners’ sugar.

Assembly:

5. Pair up the cake rounds with other rounds of similar size and shape. Put vanilla buttercream and fake “blood” into piping bags or Ziploc bags with the corners snipped off. Use a larger hole for the buttercream and a smaller one for the “blood”.

6. Pipe a circle of buttercream from the bottom of one of the cake rounds. Fill the center with “fake blood”. Place the matching cake round on top. Repeat with remaining pies.

7. Use a toothpick to make two small pricks on top of each assembled whoopie pie. Dip the toothpick into the “fake blood” and add drops to each of the pin-pricks, then drizzle some down the side of the cake.

8. Serve and enjoy.