German Chocolate Cake

1 pkg. 4 oz. Bakers German Sweet Chocolate
1/2 C boiling water
2 squares butter
2 C sugar
4 egg yolks
1 tsp. vanilla
2&1/4 C flour
1 tsp. soda
1/2 tsp. salt
1 C buttermilk, or soured milk; 1 TB vinegar added and set aside to sour.
4 egg whites stiffly beaten
Melt Chocolate in boiling water. Cool. Cream butter and sugar till fluffy beating with a hand beater. Separate the eggs, putting the whites in one mixing bowl;set aside, and add yolks one at a time to the butter mixture, beating well with each addition. Blend in vanilla and chocolate. Mix flour with soda and salt. Add alternately with buttermilk to Chocolate mixture beating after each addition till smooth. Beat egg whites and fold in carefully. Pour into cake pans or 9x13 pan. Bake 350 for 30-35 minutes.
Frosting: Combine 1 C evaporated milk, 1 C sugar, 3 slightly beaten egg yolks, 1 square butter, and 1 tsp. vanilla. Cook and stir until thickened. Add 1&1/3 C coconut and 1 cup chopped walnuts. Cool until thick enough to spread.