Finely grind nuts in food processor. Add honey, egg white, cocoa, spices and salt. Blend to paste. Add flour and mix using on/off turns until just incorporated. (NOTE: Dough will be sticky.)
Place dough on work surface heavily dusted with sifted icing sugar. Sift more icing sugar over dough. Gently roll dough out to thickness of 1cm. Cut into 2.5cm x4cm bars using knife that has been dusted with icing sugar. Arrange on greased tray, spacing 2cm apart.
Bake cookies at 140 degrees C (275 degrees F) until firm and tops appear dry, about 25-30 minutes. Cool cookies completely on racks.
To Make Icing: Blend 1/2 cup icing sugar and 2 teaspoons egg white. Mix in enough liqueur to make thick but pourable icing. Set racks on waxes paper; arrange cooled cookies on racks with edges touching. Drizzle icing over cookies in irregular lines. Separate cookies. Let stand until icing is dry. Store in airtight container.