Chocolate cake from scratch

I have been hunting for a good chocolate cake recipe for a while now, and while this one isn't perfect, it's the best I've found so far.

Ingredients:

1 egg
2 egg whites
1 1/4 c. sugar
1/2 c. butter
1/2 tsp. baking soda
1 tsp. vinegar
1/2 tsp. salt
1/2 c. cocoa
1 c. flour
1/2 c. boiling water
1 tsp. vanilla

Directions:

In a large bowl, combine eggs, sugar, and butter. Beat until light and whipped, about 4 minutes. Add soda, vinegar, salt and cocoa, beat until mixed in. Add flour, water and flavoring. Beat just until mixed. Do not over-beat. Spoon into pan (12 cupcakes or one cake) and bake at 350 degrees for 24-27 minutes.