Preheat the oven to 350°. Grease and flour 2 9" cake pans, or grease and line with parchment paper circles.
In the bowl of your stand mixer, add the flour, sugar, cocoa baking soda, and salt and mix until combined.
Add the eggs, melted butter, vanilla, and buttermilk, and mix until just combined.
Remove the bowl from the mixer and and then stir the hot coffee into the batter by hand. The batter will be runny. It’s supposed to be.
Pour into your cake pans and bake until a toothpick inserted into the center comes out clean with just a few bits of cake stuck to it. For 9 inch pans, that should be anywhere from 20-30 minutes. Start checking around 15 minutes. If you use different size pans than you will have a different baking time.
When you remove each cake from the oven, let it cool for 5 minutes, then run a knife around the edges of the pan, and carefully tip the pan over on a cooling rack. If you used parchment paper on the bottom remove it. Let cakes cool completely before frosting.