The butter and egg yolks should be at room temperature. finely grated lemon zest grater. In a small bowl mix it with sugar and mix well with a fork. In a deep pot Beat with a mixer on medium-low speed, add the butter and lemon-sugar mixture. Add the egg yolks and again defeated. Then add the flour mixed with salt, as we begin to confuse low speed and gradually increase the speed to obtain lumps. If the mixture seems very dry can continue kneading her with a wooden spatula. Then mixed with good hands, so the butter will absorb heat and melt more, taking the flour. Divide the dough into two equal parts. Flat and put a plastic foil, then one part of the dough begin to shape with his hands on fthe oil, so as to obtain a rectangle with a length of about 15 cm and a width of about 4-5 cm. Shaped dough cornering fthe oil. Similarly shape and the second part of the test and refit nice with foil. Then leave it in the refrigerator for at least 4 hours. In a large tray covered with baking paper, ordered about 5 cm apart with a sharp knife cut rectangles cookies with a thickness of about 5 mm, bake them in a preheated oven 180C degrees . Bake until a golden-brown color. Making lemon glaze: In a small bowl send down powdered sugar and add lemon juice, stirring to obtain a mixture that flows slowly from the spoon. Sprinkle cookies with icing. We leave them to dry for 1-2 hours. * The number of cookies is about 45-50.