Directions

1. Preheat oven to 350 degrees with rack in the center. Spray two 8x2-inch round cake pans with nonstick spray.
   
2. Whisk together flour, 2 cups sugar, 1/2 cup cocoa, baking soda, and 1 teaspoon salt in a large mixing bowl.
   
3. Combine water, oil, vinegar, 1 tablespoon coffee, and 1 tablespoon vanilla in a large mixing bowl.
   
4. Add to the dry ingredients and whisk just until combined, a few lumps are okay. Divide batter between pans, then bake until a toothpick inserted in the center comes out clean, 35-40 minutes. Cool cakes on a rack for 15 minutes, then invert them onto the rack. Leave cakes upside down (this flattens domed cakes) to cool completely.
   
5. To make frosting: Melt butter in a large saucepan over medium heat. Stir in 1 1/2 cups sugar, 1 1/4 cups cocoa, and 1/8 teaspoon salt. Mixture will be thick and grainy.
   
6. Combine heavy cream, sour cream, 1 teaspoon coffee in a large bowl, mixing until smooth. Gradually add cream mixture to chocolate until blended and smooth. Cook until the sugar has dissolved and the mixture is smooth and hot to the touch, 6-8 minutes. Do not boil.
   
7. Off heat, add 2 teaspoon vanilla. Cool icing at room temperature until spreadable, 2-3 hours. (Icing may be chilled until completely cold, then warmed gently in microwave until spreadable. Heat at high power in 20-second intervals, stirring well after each interval.)
   
8. When cake has cooled completely, spread frosting.