This biscotti-like cookie is derived from the Eastern European/Jewish cookie Mandelbrot. Australians adopted it, and renamed it Mandel-Melba, due to its textural similarity with the Australian favorite Melba toast (named, of course, for the opera singer Dame Melba). We've used pistachios here, with lemon and orange zests to brighten the flavor. They're not super-sweet; they're more of a cookie to have with your tea or coffee. The key to this is to slice it super-thin so it crumbles in the mouth. * Contributed by Catsrecipes Y-Group