1. Preheat oven to 350 degrees F. Lightly oil a 12-cup Bundt pan or coat it with nonstick cooking spray. Dust the pan with flour, invert and shake out the excess.
2. In a large mixing bowl, whisk together flour, white sugar, cocoa powder, baking soda, baking powder and salt. Add buttermilk, brown sugar, eggs, oil and vanilla; beat with an electric mixer on medium speed for 2 minutes. Whisk in hot coffee until completely incorporated. (The batter will be quite thin.)
3. Pour the batter into the prepared pan. Bake for 45 to 55 minutes, or until a cake tester inserted in the center comes out clean. Cool the cake in the pan on a rack for 10 minutes; remove from the pan and let cool completely.
4. To make icing: In a small bowl, whisk together confectioners' sugar, vanilla and enough of the buttermilk or milk to make a thick but pourable icing. Set the cake on a serving plate and drizzle the icing over the top.

Yield: 16 servings