Preheat oven to 350 degrees.
Grease and flour two 9 inch pans, line bottom with parchment paper circles and set aside. I USED THREE 6 INCH PANS. THIS WILL MAKE TWO SMALL 3-LAYER CAKES.
In a bowl of stand mixer, stir together flour, cocoa, sugar, baking soda, and salt.
Add eggs, buttermilk, melted butter, and vanilla; beat until smooth, about 2 to three minutes.
Remove bowl from mixer and stir in hot coffee with rubber spatula, the batter will be very runny.
Pour into pans and bake on middle rack for 35 minutes or until toothpick comes out clean with a few crumbs attached.
Allow to cool on wire rack for 15 minutes.
Run a butter knife around the pan.
Invert pans onto racks.
Cool completely before frosting