We also call this 20 bowl cake. It's more work than most cakes but it is really good. I use this cake for shaped birthday cakes and regular ones too unless another one is requested.
Double Devil's Food

Whisk together in large glass bowl:
1 1/2 cups cocoa
2 cups brown sugar

Add and mix:
1 cup milk
2 egg yolks

Add then heat to a boil in microwave stirring every minute:
4 oz margarine

Let chocolate pudding cool.

Beat:
8 oz margarine
4 yolks
2 cups sugar

Mix:
3 1/2 cups flour
2 tsp baking soda

Mix:
1 1/2 cups milk
2 tsp vanilla

Add flour in 3 parts alternating with milk to margarine mixture. Scrap down and beat smooth with each addition.

Mix in cooled chocolate pudding.

Fold in:
4 whipped egg whites

Pour into a lined metal 9x13" and a 9x9" pan (or use three 8" and three 9" round pans but don't bake as long)

Bake at 325ºF for 60 min.