1 (4 oz.) German sweet chocolate bar
1 c. boiling water
1 c. butter
2 c. brown sugar, packed
2 eggs, separated
2 tsp. baking soda
1/2 c. buttermilk
2 1/4 c. cake flour (not all-purpose)
1/2 tsp. vanilla
Frosting (see below)

Break bar into pieces; dissolve in hot water. Let cool to room temperature. Cream butter and sugar until light and fluffy. Beat in yolks and then chocolate mixture. Dissolve soda in buttermilk. Sift flour. Beat in flour on low speed or by hand, alternately with buttermilk, beginning and ending with flour. Beat well after each addition. Beat egg whites until stiff peaks form. Fold gently into batter with vanilla.

Bake 25 to 30 minutes at 350 degrees, in floured and buttered pan. Let rest 10 minutes; turn out on wire rack until cool. Frost with frosting below.

FROSTING:

Put 6 tablespoons flour in saucepan; slowly whisk in 1 1/2 cups milk until smooth. Cook over medium high heat until it comes to a boil and is thick, stirring constantly. Cool to room temperature. Cream 1 cup butter with 1 cup sugar. Beat in flour mixture and continue beating 5 minutes on medium high. Blend in 1 1/2 teaspoons vanilla. This is really delicious and worth the time to make.