Creating the Black Velvet Halloween Cake is a straightforward process. Follow these steps for best results:

1. Preheat the Oven: Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
2. Mix Dry Ingredients: In a large bowl, combine flour, sugar, cocoa powder, baking soda, and salt. Whisk until well combined.
3. Combine Wet Ingredients: In another bowl, mix buttermilk, vegetable oil, eggs, vanilla extract, and vinegar. Whisk until smooth.
4. Combine Mixtures: Gradually add the wet ingredients to the dry ingredients, mixing until just combined.
5. Add Boiling Water: Carefully stir in the boiling water. The batter will be thin, but this is normal.
6. Bake the Cake: Pour the batter evenly into the prepared cake pans. Bake for 30-35 minutes or until a toothpick inserted in the center comes out clean.
7. Cool the Cakes: Allow the cakes to cool in their pans for 15-20 minutes before transferring them to wire racks to cool completely.

Once the cakes are fully cooled, you can move on to frosting and decorating!