Sift flour, baking powder and salt together. Melt shortening, add brown sugar. Stir well, cool slightly. Add eggs, one at a time, beating well. Add dry ingredients, nuts and chocolate. Pour into a greased 9" square pan (or equivalent size), bake 350° oven for 20-35 minutes. Check for doneness by testing with a toothpick in the center, if toothpick is clean, then squares are done. Cut into squares when completely cooled.