In a small pot, combine orange zest and juice, fennel seeds and aniseed. Bring to the boil and simmer until reduced to 2 cm depth. Transfer to a large mortar and pestle and grind the seeds in the liquid. Whisk the zest and seed mix with sugars and eggs.
In a large bowl sift the flours and salt, and then rub in the butter until it resembles breadcrumbs. Make a well in the centre and pour in the combined egg, zest and seed mix. Bring it together to form a firm dough that is not too stiff and dry (if it is dry, add a dash of milk to soften).
Preheat oven to 180°C.
Oil your hands and roll walnut-size portions into crescent shapes. Lightly beat the extra egg to make an egg wash. Brush biscuits with egg wash and bake for 10 to 12 minutes.