This has been a long time favorite of mine and my mom used to make them all the time. They are relative easy to make and give you a very moist and not too sweet chocolate cake. I have seen very many variations on this recipe, but most are pretty similar and almost non-fail. Here is the one I use.
For the cake:
2 cups flour
2 cups sugar
1 tsp. baking powder
1/2 tsp. salt
1 cup butter
1/3 cup cocoa
1 cup water
2 eggs
1/2 cup buttermilk
2 tsp. vanilla
Grease and flour either a 15x10x1 inch jelly roll pan or a 9x13 cake pan. Then in a large bowl mix together flour, sugar, baking soda and salt.
In a large saucepan, bring to a boil the butter, cocoa and water, stirring well all the time. Beat the boiling mixture into the dry ingredients, then beat in the eggs, vanilla and buttermilk. Spread in the bottom of the prepared pan and bake at 350 degrees 25 minutes for the jelly roll pan or 35 minutes for the 9x13 cake pan or until a toothpick stuck in the center of the cake comes out clean.
While the cake is baking prepared the frosting:
1/4 cup butter
4 tbsp. cocoa
1/4 cup butter milk
approximately 2 1/4 cups powdered sugar
1 tsp. vanilla
In a saucepan bring the butter, cocoa and buttermilk to a boil. Remove from the heat and beat in the vanilla and powdered sugar. It should not be too thick, as you want it to spread easily. Add more buttermilk if needed. Spread the warm frosting over the hot cake as soon as it comes out of the oven. Allow to cool completely before cutting. Refrigerate any leftovers. As always, enjoy!
