Preheat oven to 350° F. Line two 8-inch round baking pans with parchment paper and/or spray well with nonstick cooking spray and set aside.
In a large bowl, whisk flour, cocoa powder, baking soda and salt together to combine. Set aside.
In a liquid measuring cup, stir buttermilk, vanilla extract, vinegar and red food coloring. Set aside.
In a separate large bowl, mix oil and sugar together until combined.
Mix in eggs and egg white, one at a time, until mixture becomes lighter in color, about 90 seconds.
Alternate adding in flour mixture with milk mixture, being sure to start and end with flour. Scrape the sides and mix again to ensure a smooth batter.
Divide evenly between baking pans and smooth the top. Bake 28-35 minutes in the lower part of the oven. If you're using three cake pans instead of two, you will need to bake this cake 22-30 minutes.
Cake will be done when a toothpick comes out clean or mostly clean with a few moist crumbs. Cool 15-20 minutes in cake pans before trying to invert on cooling racks.
Once you can handle the warm pans with your bare hands, you can flip them out. Cool completely before frosting and decorating.