Sift together sugar and flour. Melt butter, add cocoa and water. Bring to a boil and pour over flour and sugar. Then add buttermilk, eggs, soda, cinnamon, and vanilla. Cook in sheet cake pan at 350 degrees about 35 minutes. Ice while hot.
Bring to a boil and remove from heat:
1 stick butter, 4 tablespoons cocoa, and 6 tablespoons milk.
1 box powdered sugar, 1 teaspoon vanilla, and 1 cup chopped pecans.