Preheat the oven to 350 degrees. Grease and flour three, 9-inch round layer cake pans.
Sift flour, baking soda and salt together. Heat the chocolate and milk in the top of a double boiler until the chocolate melts. Add the brown sugar and beat until smooth. Cool and add the vanilla. Cream the shortening with the granulated sugar until fluffy. Add the eggs, one at a time, beating thoroughly after each is added. Add the sifted dry ingredients and the cooled chocolate mixture alternately in small amounts, beating well after each addition. Pour into the prepared pans and bake for 30 to 35 minutes, or until a cake tester comes out clean when inserted in the middle of the cake.
Source: “250 Classic Cake Recipes”, Culinary Arts Institute, Consolidated Book Publishers Inc., 1940