In mixer bowl, cream butter at medium speed. At low speed, blend in flour, soda, salt and sugar, which have been sifted together. Add 3/4 cup milk. Beat 2 minutes at medium speed. Add eggs, melted chocolate and remaining milk; blend. Scrape bowl frequently. Beat 1 minute at medium speed. At low speed, add nuts and blend well. Turn batter into greased 9 x 13 pan. Bake at 350~ for 45 minutes or until done. Cake may also be baked in 2, 9" pans at 375~ for 25 minutes or until done. Omit nuts. NOTE: Cocoa may be substituted for chocolate. Sift 2/3 cup cocoa with dry ingredients.