For the dough, sieve the flour with salt and baking powder, add the softened butter, the egg white and the water. Now knead the dough by hand or with the dough hook, then let it rest for 30 minutes.
For the nut filling, chop the walnuts and mix with sugar and cinnamon or helm.
For the date filling, core the dates and heat them gently in a pan with butter, add the chopped walnuts.
Roll out half of the dough thinly with a rolling pin. Spread the date mixture evenly over it with a spoon. Roll up the dough like a Swiss roll and cut it into slices with a knife at intervals of 2 centimeters. Place the cookies on a parchment-lined baking sheet.
Roll out the other half of the dough thinly with a rolling pin and then cut out circles with a glass of dough. Fill with the nut mixture and fold up in a crescent shape, pressing down the edges. Place the filled biscuits on the baking sheet and brush all of them with the egg yolk using a brush. If you want, you can sprinkle some sesame on the cookies.