In a medium bowl, cream together the butter and sugar. Stir in the golden syrup and egg yolk. Gradually stir in the flour until fully incorporated. Cover and chill for at least 1/2 hour.
Preheat oven to 170 degrees C. Lightly grease baking trays.
Roll dough into 3cm balls, dip them in the egg white then roll them in the nuts. Place biscuits on the prepared baking tray 5cm apart. Using your finger, make an indention in the centre of each biscuit.
Bake for 20 to 25 minutes in the preheated oven or until golden. Fill each indention with a small amount of jam while biscuits are still warm. Allow biscuits to cool on the baking trays.