Preheat the oven to 350 F (175 C). Grease/flour two cake pans (9 in.). Stir in a bowl the sugar, flour, baking soda, baking powder, cocoa, and salt. Add in the milk, eggs, vanilla, and mix up for 3 min. Then, add in the boiling water. Pour out the batter into the two pans and bake for 30-35 min. until done. Let cool before removing from the pans (10 min.). Then, for the frosting, cream together butter with cocoa and the confectioners’ sugar. Add in by alternating the vanilla and milk and beat until it is smooth. Then, when the cake is cooled, split each layer horizontally. Cover each layer with frosting and stack on a serving plate. Also frost the outside of the cake. Let set and enjoy!