In the stand mixer, using the paddle attachment, sift flour and salt in mixing bowl. Cut and add cold butter into the mixing bowl distributing evenly, and mix at low speed until the butter is broken into smaller pieces and coated with flour, about 15-20 seconds. You want to still see larger pieces of butter throughout.
Continue at a low speed, add the egg yolks, and gradually the ice water, mixing until the water is absorbed and the dough comes together, then stop mixing, about 10 seconds. DO NOT overmix.
Transfer the dough to a lightly floured surface, and dust the top of the dough as well and work with your hands to pat down and form a rectangle, but still maintaining a thickness to about ¾ inch. Wrap with saran wrap tightly and place in the refrigerator to chill for 20 minutes. Remove from the refrigerator and roll out to about ½ inch thickness and fold in thirds, envelope style. Wrap again, chill for another 20 minutes, and repeat this one more time.
The final rolling and wrapping, place in a zip-lock bag and chill for 4 hours or overnight.
Preheat oven to 425°F. Line baking sheets with parchment paper.
Take out dough from refrigerator and cut one-third, and put the remaining two-thirds back in the refrigerator to say cold. Roll out the one-third to ¼ inch thickness. Then cut into 3 inch squares. Using a teaspoon, fill with desired filling at the lower half of one corner of the square, the fold over until you reach the end of the opposite corner.
Place 2 inches apart on prepared baking sheets, and bake for 12-15 minutes, until golden in colour. Allow to cool for 5 minutes, remove and place on cooling rack.
Serve once cooled and dust with icing sugar.
Storing: These crescents or Kifli's can be stored up to about 3 weeks in the refrigerator. If you have cold cellar, that would even be better. My mom would store them in the cold cellar and it maintained the texture and flakiness to these Kifli's, however, today, not everyone has a cold cellar, so the next best option is the refrigerator. Before serving, dust them with icing sugar.
