Make the dough: in a large bowl or in a food processor, combine flour, powdered sugar, salt and baking powder. Add butter and blend until crumbs are formed.Add egg yolk, vanilla extract and 1 tablespoon of milk. Blend until dough is formed, if needed add another tablespoon of milk. Do not over blend.Flatten the dough into a disk form, cover with plastic wrap and refrigerate for 30 minutes.Preheat oven to 170C (340F).Take the dough out of the fridge, roll the dough into about 1/4-inch (1/2 cm) thick. cut into 6-8 cm circles. Fill each circle with date paste and seal as shown on the video. Combine the leftover dough, roll in and repeat the process.Arrange the cookies on a baking tray lined with parchment paper and bake for 12-16 minutes, until slightly golden.Allow to cool, then dust with powdered sugar.Notes:You can use any filling that you like, such as: Chocolate spread (Nutella), poppy seed filling (traditional Jewish filling), jam and more.To add more flavour, you can add to the date filling some cinnamon and chopped nuts.To make the dough you can use food processor, hand dough blender as I used in the video or even by hand.It is important to not overmix the dough, otherwise it will become hard.