Preparation / Directions:
Preheat the oven to 350 degrees. To make the cake, combine the chocolate, milk, brown sugar, vanilla and 1 egg yolk in the top of a double boiler. Cook, stirring over hot water until smooth. Remove from the heat and let cool.
Sift the flour with the baking soda and salt. Beat the butter in a large bowl of an electric mixer until light. Add the remaining 2 egg yolks, one at a time, beating thoroughly after each addition.
Beat in the chocolate mixture in 3 parts, alternating with the flour mixture. Do not overbeat. Beat the egg whites until stiff; fold into the batter.
Pour the batter into 2 greased and floured 9-inch round cake pans. Bake until a toothpick inserted in the center comes out fairly clean, 20 to 30 minutes. Let cool on a wire rack before unmolding.
To make the icing, melt the chocolate in the top of a double boiler over hot water. Stir in the condensed milk until smooth. Sitr in the butter, bit by bit, until smooth. Whisk in the egg yolk and vanilla and cook until slightly thickened. Let cool slightly, then smooth over the bottom layer; place other layer on top, then ice the sides and top of the cake.