Preheat oven to 350°F.
Grease pans and line with parchment.
In a bowl, whisk flour, cocoa, baking soda, salt.
In another bowl, beat sugar, oil, and eggs.
Add vanilla, vinegar, and buttermilk. Mix well.
Slowly add dry ingredients to wet mixture.
Add black food coloring. Mix until even.
Divide batter evenly between pans.
Bake for 30–35 minutes.
Test with toothpick; it should come out clean.
Let cakes cool on wire rack.
Beat cream cheese and butter until smooth.
Add powdered sugar slowly. Mix well.
Stir in vanilla for flavor.
Level cakes with serrated knife.
Place one cake layer on stand.
Spread frosting evenly on top.
Place second cake layer on frosting.
Frost entire cake with remaining cream.
Chill slightly before serving.