In a large bowl, combine flour, sugar, cocoa powder, salt, baking soda, and baking powder. Mix well.
Add in vanilla, eggs, buttermilk, and vegetable oil mixing until smooth. Pour in hot water and mix well. Batter will be very thin.
Pour batter into prepared pan. Bake in preheated oven for 32-36 minutes, or until a toothpick inserted in center comes out clean.