Preheat Oven to 350 degrees.
In a 3-quart mixing bowl, sift together, sugar, flour, and salt. Set aside.
In a heavy saucepan or 4-cup glass microwaveable measuring cup melt butter, water, and cocoa together. Mix well.
In a second heavy saucepan or 4-cup glass microwaveable measuring cup mix together, eggs, buttermilk, soda, and vanilla. Mix well and let cool
When cooled, mix all wet ingredients together.
In the mixing bowl, combine wet ingredients and beat until all ingredients are incorporated together.
Pour mixture into a slightly-greased and floured pan or pans.