Knead flour and butter (the dough musthave the consistency of the sand). You can use also a blender.
Add the sugar, the yolks and the lemon twist and knead strongly with your hands until the dough will be solid.
Give the shape of a ball, wrap it in a cellophane film for food and let it rest in the fridge for 30 minutes at least. Divide the dough into two halfs and roll one of them with a rolling pin until you obtain a circle of about 4 millimeters high. Put the dough into a removable mold, cutting the exceeding dough.Poke the dough with a fork, then fill with the jam. Turn on the oven at 180°C. Roll the remaining dough, then cut some stripes about half a centimeter large. Put them on the pie forming some rhombus. Put it in the oven and cook for about 25-30 minutes until the dough is gold. Bake the cake and leave to cool (it is better to remove the cake from the mold when it is completely cold, so it doesn't break).