Sift both types of flour into a mixing bowl. Add in chilli powder, pepper, salt, caraway seeds and castor sugar to mix.
Rub in diced butter, then stir in egg yolk and water to form a smooth dough. If the dough is too soft, wrap with cling film wrap and chill in the refrigerator for 1520 minutes.
Roll mixture into cherry-sized balls. Arrange on prepared cookie trays and press lightly with a fork. Brush lightly with beaten egg white and sprinkle with a bit of caraway seeds. Bake in preheated oven at 180°C for 1215 minutes or until lightly golden brown.