Preheat oven to 350 degrees F. Grease and flour 2 (9-inch) round layer cake pans, or spray with Bakers Joy.
Sift flour and cocoa together. Beat sugar and eggs together in a large bowl.
In a separate bowl mix together oil, vinegar, food coloring, and vanilla. Add to the bowl of eggs and sugar and beat until combined.
Add the flour mixture and the buttermilk to the wet mixture by alternating the buttermilk and dry ingredients. Start with the flour and end with the flour.
Pour batter into pans. Tap them on the table to level out the batter and release air bubbles. Bake for 25-28 minutes or until a toothpick inserted near the middle comes out clean. Be careful not to over bake or you’ll end up with a dry cake.
Let layers cool on a wire rack for about 10 minutes before turning out of pan. Let cool completely before frosting.