Heat over to 350F. Lightly grease and flour the baking pan(s). Melt chocolate in double boiler. Sift flour, tartar, soda and salt together in large mixing bowl. Add eggs, butter, milk, chocolate and vanilla. Mix thoroughly. Add boiling water and beat 1 min. Pour into pan(s) and bake for 30-40 mins until toothpick comes out clean. Cool thoroughly before frosting if desired. Enjoy.