Preheat oven to 350°F.
Grease two 9x13 pans and line the bottom with parchment paper.
Add flour, sugar, cocoa powder, salt, baking powder and baking soda to your mixing bowl (I use a stand mixer with the whisk attachment). Stir until combined.
In a separate medium bowl, whisk together the oil, buttermilk, eggs and vanilla. Once combined, add in the coffee slowly so you don't cook the eggs.
Pour the wet ingredients into the dry ingredients and stir slowly until combined. Then mix on high for two minutes, scraping the sides halfway through.
Distribute the batter evenly between the two prepared pans and bake for 20-25 minutes, or until a toothpick comes out clean. (A few moist crumbs sticking to the toothpick is fine, but you don't want it gooey)
Cool cakes for a few minutes. Run a butter knife around the outside of each pan, and turn the cakes out onto a cooling rack and carefully remove parchment paper. Let cool completely.