• Preheat oven to 350 degrees Farenheit, and lightly grease an 18 x 13 cake pan.
• In a mixing bowl, combine flour, sugar, and salt. Set aside.
• In a saucepan, melt butter over low heat. Add cocoa and stir.
• Add hot water. Allow butter, cocoa, and water to boil in saucepan for 30 seconds.
• Pour over flour mixture in mixing bowl, and mix lightly to cool.
• In a large measuring cup, measure the buttermilk; stir in beaten eggs, baking soda, and vanilla.
• Gently mix liquids into butter/chocolate mixture.
• Pour into pan and bake for 20 minutes.

Frosting

• Melt butter in saucepan over low heat. Add cocoa and stir to combine. Then remove from heat.
• Add the milk, vanilla, powdered sugar, and cinnamon. Whisk together until shiny and smooth.
• Pour over warm cake. Spread with a spatula if necessary.