1. Preheat oven to 350°F and line a cupcake pan with liners.
2. Combine crushed Oreos, butter, and sugar. Press 1 tablespoon into each liner.
3. Beat cream cheese and sugar until creamy. Add eggs, cocoa, sour cream, buttermilk, vanilla, vinegar, and food coloring. Mix until combined.
4. Fill each liner 3/4 full with the cheesecake mixture.
5. Bake for 25 minutes or until centers are set. Cool and chill overnight.
6. For frosting, beat cream cheese and butter until smooth. Add powdered sugar and vanilla, mixing until fluffy.
7. For edible blood, mix corn syrup and water, add red and blue food coloring, and thicken with cornstarch.
8. Top cheesecakes with frosting and drizzle with edible blood if desired.