In mixing bowl, combine until smooth flour, baking powder, salt, sugar, 3 tablespoons cocoa, milk, vanilla, shortening or margarine. Add nuts. Pour into greased 8-inch square pan. Combine brown sugar and 2 tablespoons cocoa; sprinkle over batter. Pour hot water over all. Bake at 350 degrees for 45 minutes. Serves 6 to 8. Serve warm, topped with ice cream, : Baking time: 45 minutes