In a large mixing bowl, combine the flour, sugar, salt and baking soda. In a large saucepan over medium heat, bring cocoa, water, oil and butter to a boil. Gradually add to dry ingredients; mix well. Combine eggs, buttermilk and vanilla; gradually add to batter and mix well (batter will be very thin). Fill paper-lined muffin cups three-fourths full. Bake at 350° for 15-20 minutes or until a toothpick comes out clean. Cool for 10 minutes before removing from pans to wire racks to cool completely.

For icing, in a heavy saucepan, combine the brown sugar, butter and milk. Cook and stir over low heat until sugar is dissolved. Increase heat to medium. Do not stir. Cook for 3-6 minutes or until bubbles form in center of mixture and syrup turns amber. Remove from the heat; transfer to a small mixing bowl. Cool to room temperature. Gradually beat in confectioners' sugar. Spread over cupcakes.