- Preheat oven to 350° and line 3 9" cake pans with parchment and nonstick spray.  
- In the bowl of an electric mixer, add flour, sugar, baking powder, salt and cocoa powder.  
- In a separate bowl, combine the oil, eggs, buttermilk, vanilla extract, and vinegar.  
- With the mixer on low speed, slowly stream in the wet ingredients.  
- Stop the mixer and scrape the bowl, making sure all dry ingredients are incorporated.  
- Turn the mixer to medium high speed and mix for 4 minutes.  
- Evenly distribute the batter into 3 9" cake pans, and then bake for 25-30 minutes, or until the top of the cake springs back when touched.