Sift the flour, cocoa powder, baking soda and baking powder into the bowl of an electric mixer using a sifter or a wire-mesh strainer.
Add salt and sugar to the bowl, and with the mixer set to low speed, beat for 30 seconds or so until combined.
In a separate bowl, whisk eggs, buttermilk, oil, and vanilla.
With the mixer set to low, add the wet mixture to the dry mixture and blend until just combined.
Beat in the coffee until fully incorporated.