Heat oven to 350°F. Grease 13x9-inch pan with shortening; lightly flour. In large bowl, mix flour, sugar, cocoa, 1 teaspoon of the cinnamon, the baking soda and salt. Add butter, brewed coffee, buttermilk, vanilla and eggs; mix with wire whisk until well blended. Pour batter into pan.
Bake 40 to 44 minutes or until toothpick inserted in center comes out clean. Cool on cooling rack 30 minutes.
In small bowl, mix coffee granules and warm water. In medium bowl, mix frosting, remaining 1/4 teaspoon cinnamon and the coffee mixture until smooth. Spread frosting over warm cake. Cool 1 hour or until completely cooled. Serve with a dollop of whipped topping and sprinkle with additional cinnamon.