Use gel food coloring for a deeper red velvet color without adding too much extra liquid to the batter.
Do not overmix the batter once the flour is added. Mix only until everything is incorporated for soft, tender cupcakes.
Make sure the cupcakes are completely cool before adding cream cheese frosting.
Keep the cream cheese and butter softened, but not overly warm, so the frosting stays thick enough to pipe.
Add the edible blood shortly before serving for the freshest, most dramatic drip effect.
For a more realistic look, let the blood fall unevenly rather than trying to make every cupcake match.
Storage
Store the frosted cupcakes in an airtight container in the refrigerator for up to 3–4 days because of the cream cheese frosting.
Allow them to sit at room temperature for about 15–20 minutes before serving for the best texture.