In a large bowl or using a food processor, beat the softened butter and sugar together until the mixture is light and creamy.

Gradually add the eggs, mixing well after each addition until fully incorporated.

Stir in the chopped roasted hazelnuts and the ground hazelnuts, followed by the flour. Mix until a smooth dough forms.

Wrap the dough in plastic wrap and chill it in the refrigerator for about 1 hour.

After chilling, roll out the dough between two layers of plastic wrap to a thickness of about 0.5 cm.

Cut the rolled dough into strips about 7×2 cm and place them on a baking sheet lined with parchment paper.

In a small bowl, whisk together the egg yolk and milk, then brush this mixture over the cookies.

Bake in a preheated oven at 200 °C (400 °F) for about 12-15 minutes, or until they are lightly golden brown.

Once cooled, dip one side of the cookies into melted chocolate, place them back on the tray, and let them set completely.