Preheat the oven to 350°F Grease two 9-inch layer pans and line the bottoms with wax or parchment paper. Grease again.
To prepare cake, heat 1/2 cup of the milk with the cocoa powder in a small pan, stirring until mixture thickens. Cool.
Cream the butter and sugar together very well. Beat in the egg yolks, one at a time. Beat in the cooled cocoa mixture.
Stir in the vanilla, flour, remaining milk, dissolved baking soda and nuts. Beat the egg whites until stiff and fold together. Spoon into prepared layer pans and bake about 25 minutes, or until done. Cool on a rack.
To prepare frosting, place the sugar and water in a saucepan and heat, stirring, until sugar dissolves. Boil without stirring until sugar syrup reaches the soft ball stage or 238°F degrees on a candy thermometer.
Add the salt to the egg whites and beat into the hot sugar in a steady stream. Beat in the corn syrup and cream of tartar. Beat in the vanilla and continue beating until mixture is spreading consistency. Use to fill and frost the layers. Yield: 6 to 8 servings.