Preheat the oven to 350°F and grease 3 9" cake pans.
In a large mixing bowl, mix together the melted butter and granulated sugar.
Beat in the eggs, one at a time.
Mix in the salt, baking powder, baking soda, and vanilla extract.
Mix 1 cup of cocoa powder.
Add in the buttermilk and mix thoroughly.
Mix in the remaining 1 tbsp of cocoa powder and 1 cup of sifted flour.
Mix in the hot water.
Add in the rest of the sifted flour.
Split the batter between the three pans and bake for about 40min or until a toothpick emerges clean.