Mix flour, cocoa, sugar, soda, cinnamon and salt together in large mixing bowl.
Bring water and butter to a boil. Add instant coffee and vanilla to water.
Pour wet ingredients into dry ingredients and mix well.
Add eggs and buttermilk and mix well.
Bake in greased sheet cake pan at 350º for 20-25 minutes. Done when toothpick inserted in center comes out clean.
Frost in pan with Glossy Cocoa Icing (posting next).