Old Fashioned Chocolate Cake and Glossy Chocolate Frosting

I am not the world's biggest fan of chocolate cake but I am always looking for new recipes for it because Chris IS the world's biggest fan of chocolate cake.  This ingredient is not listed in the recipe as it is written but Chris would contend that you will need most of a gallon of milk if you're going to eat a piece or two of this cake.  I may ask my Mom and Aunt...if this is similar to a recipe my Grandma used years ago...did we have a family chocolate cake recipe that called for vinegar

3 C. all purpose flour
2 C. sugar
1/2 C. unsweetened cocoa
2 tsp. baking soda
1 tsp. table salt
2 C. hot water
3/4 C. vegetable oil
2 tbsp. distilled white vinegar
1 tbsp. instant coffee granules
1 tbsp. vanilla

Preheat oven to 350 degrees with rack in the center.  Spray 2 round cake pans with nonstick spray.

Whisk together flour, sugar, cocoa, baking soda, and salt in a large mixing bowl.

Combine water, oil, vinegar, instant coffee and vanilla in a large measuring cup.  Add to the dry ingredients and  whisk just until combined--a few lumps are OK.  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.

Glossy Chocolate Frosting

1 stick unsalted butter
1 1/2 C. sugar
1 1/4 C. unsweetened cocoa powder
Pinch of salt
1 1/4 C. heavy whipping cream
1/4 C. sour cream
1 tsp. instant coffee granules
2 tsp. vanilla extract

Melt butter in a large saucepan over medium heat.

Stir in sugar, cocoa, and salt.  Mixture will be thick and grainy.

Combine heavy cream, sour cream, and instant coffee in a large measuring cup, 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.

Off heat, add vanilla.  Cool icing at room temperature until spreadable, 2-3 hours.  Icing can be refrigerated and then warmed gently in the microwave until spreadable.  Heat at high power in 20 second intervals, stirring after each interval.