Using flour, butter, not too soft, yolk, salt, sugar and cinnamon quickly make a smooth dough, wrap the dough in cling film and refrigerate for 1 hour, line a baking sheet with paper, preheat the oven to 180 degrees.
Roll out the dough about finger thick on a floured work surface. A regular square should be created. Brush the surface of the dough with the beaten egg and sprinkle with granulated sugar. Cut small cubes with a knife and place on the baking sheet. Bake in the oven for about 15 minutes.