Preheat the oven to 325 degrees F. Spray one 8-inch round cake pan with non-stick spray, line with parchment paper, and spray again. Set aside.
Combine the flour, sugar, cocoa, baking soda, baking powder, and salt into the bowl of an electric mixer fitted with a paddle attachment and mix on low speed until combined.
In another bowl, combine the buttermilk, water (or coffee), oil, eggs, and vanilla.
With the mixer on low speed, slowly add the wet ingredients to the dry, scraping the bottom of the bowl with a rubber spatula.
Bake for 25 to 30 minutes, or until a toothpick inserted in the center of the cake comes out with a few moist crumsb on it.
Cool in the pan for 10 minutes, then turn them out onto a cooling rack and cool completely or serve warm with ganache.