1. Preheat the oven to 350°F (175°C) and line a 12-cup muffin pan with cupcake liners.

2. In a bowl, sift together the flour, cocoa powder, baking powder, baking soda, and salt.

3. In a separate bowl, beat the sugar, eggs, vegetable oil, and vanilla extract until creamy.

4. Alternate adding the dry ingredients and buttermilk into the wet mixture, stirring until just combined.

5. Divide the batter evenly among the liners, filling each about two-thirds full.

6. Bake for 18-20 minutes or until a toothpick inserted in the center comes out clean.

7. Allow cupcakes to cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.

8. Stir the raspberry jam until smooth and glossy; mix in red food coloring if desired and warm briefly to thin.

9. Beat the softened butter until creamy, then gradually add powdered sugar, heavy cream, and vanilla extract; whip until light and fluffy.

10. Frost the cooled cupcakes using a piping bag or spatula to create smooth tops.

11. Use a clean straw or toothpick to make two small puncture marks on each frosted cupcake.

12. Drizzle the raspberry “blood” filling over the bite marks, allowing it to drip naturally down the sides.

13. Chill the cupcakes for 10-15 minutes to set the frosting and “blood” before serving.