To toast the hazelnuts
Without adding any oil, toast the nuts in a frying pan for approx. 3 mins., remove, leave to cool.
Place the butter in a bowl, mix in the sugar and salt. Add the eggs and continue to stir until the mixture becomes lighter in colour.
Add the ground nuts, toasted nuts and flour, quickly combine to form a dough.
Flatten the dough, cover and leave to chill for approx. 2 hrs.
On a lightly floured surface, roll the dough out to a thickness of approx. 1 cm, cut into approx. 1 x 7 cm sticks.
Place the sticks on two baking trays lined with baking paper, brush with egg yolk.
Bake each tray for approx. 10 mins. in the centre of an oven preheated to 220°C. Remove from the oven, allow to cool slightly on the tray. Transfer the nut sticks to a cooling rack, leave to cool.