01 -
Preheat oven to 175°C. Grease and flour two 23-cm round cake pans or line with parchment paper.
02 -
In a large bowl, beat softened butter and granulated sugar until light and fluffy.
03 -
Add vegetable oil and mix until well combined. Incorporate eggs one at a time, then blend in vanilla extract and white vinegar.
04 -
In a separate bowl, sift together flour, black cocoa powder, unsweetened cocoa powder, baking powder, baking soda, and salt.
05 -
Add dry ingredients to the wet mixture in alternating additions with buttermilk, starting and ending with dry ingredients. Mix gently until just incorporated, then add black food coloring gradually to achieve desired shade.
06 -
Divide batter evenly between prepared pans and smooth the surfaces. Bake for 25–30 minutes or until a toothpick inserted in the center comes out clean.
07 -
Allow cakes to cool in pans for 10 minutes. Remove cakes from pans and transfer to a wire rack to cool completely.