Combine 700 g flour, 525 g butter, 275 g sugar, 275 g hazelnuts, juice from 1½ lemons, 2 egg yolks, and 3 tablespoons cinnamon powder. Knead for 2–3 minutes until smooth. Wrap in cling film and refrigerate overnight.
The next day, roll out the dough on a floured surface to 3 mm thick. Cut into rounds using a small notched cookie cutter and place on a baking sheet lined with parchment paper.
Bake at 180°C (350°F) for 10 minutes until the edges are golden brown.
Cool the cookies on the baking sheet for 5 minutes, then transfer to a wire rack and cool completely for about 15 minutes.