1. Position a rack in the center of the oven.  Preheat oven to 350°.  Lightly butter bottom of two 9-inch round cake pans.  Line with parchment rounds.  Butter parchment and sides of pans.  Dust with flour.  Set aside. 

 2.  In the bowl of a stand mixer fitted with the paddle attachment, combine sugar, flour, cocoa, salt, baking powder, and baking soda, mixing on low speed.  Add eggs, oil, and milk, mixing to combine.

 3.  Increase speed to medium, and beat for 2 minutes.  Reduce speed to low, and add 1 cup boiling water.  (Batter will be soupy.)  Divide batter evenly between prepared cake pans. 

4.  Bake until a wooden pick inserted in center comes out clean, 30 to 35 minutes.

 5.  Remove from oven, and let cool in pans on a wire rack for 5 minutes.  Transfer to a wire rack, and let cool completely.

 6.  To frost cake, place one cake layer on a serving plate.  Spread Chocolate Frosting with a hot palette knife or icing spatula to give the frosting a beautiful shine.  (To heat a knife, run it under hot tap water, and dry with a towel.)  Spread about 3/4 cup frosting over top of first layer.  Top with second layer.  Spread remaining frosting over top and sides of cake, heating knife again as necessary.