Black Magic Cake

This cake is the bomb, as my son says. If you are a chocolate lover~beware. You will be addicted. I have been making this cake for more years than I like to admit and I still am asked to bring it to family get-togethers and whatnot. Enough is enough, but it is GOOD.
NOTE: The instant coffee is a must. Make sure they are heaping spoons of coffee!

1 3/4 cups unsifted flour
2 cups sugar
3/4 cup cocoa
2 tsp baking soda
1 tsp baking powder
1 tsp salt
2 eggs
1 cup strong black coffee (or 2 tsp instant coffee plus 1 cup boiling water)
1 cup buttermilk or sour milk*
1/2 cup vegetable oil
1 tsp vanilla

Combine flour, sugar, cocoa, baking soda, baking powder and salt in large mixer bowl.

Add eggs, coffee, buttermilk or sour milk, oil and vanilla; beat at medium speed for 2 minutes. (Batter will be thin)

Pour batter into a greased and floured 13x9x2-inch pan or two 9-inch layer pans.

Bake at 350*F for 35 to 40 minutes for oblong pan, 30 to 35 minutes for layer pans or until cake tester inserted in center comes out clean.

Cool 10 minutes; remove from pans. Cool completely; frost with Buttercream Chocolate Frosting.

* To sour milk; use 1 Tbsp vinegar plus milk to equal 1 cup.

Buttercream Chocolate Frosting:
3/4 cups cocoa
2 2/3 cups powdered sugar
6 Tbsp butter
4-5 Tbsp milk or water
1 tsp vanilla

Combine cocoa with powdered sugar. Cream butter with 1/2 cup of cocoa mixture in a small bowl; add remaining cocoa mixture alternately with milk; beating to spreading consistency. Blend in vanilla.

NOTE: For a glossier frosting , add 1 Tbsp corn syrup to the mixture.