1 cup (250g) unsalted butter, cold, cut in 16 pieces
1 egg yolk
Generous 1/2 cup milk, or more if needed
In a large bowl, whisk together the flour and salt. With a pastry blender, cut the butter into the flour until the larger remaining chunks are the size of small peas.
Drop the egg yolk into a liquid measuring cup and add milk until you reach exactly 2/3 cup (you'll use about ½ cup plus 1 tablespoon). Mix the egg yolk and milk with a fork until combined, then add it to the flour mixture all at once. Mix the dough with a fork until you can gather most of it into a ball. This is most easily done in the bowl; if it seems any drier or more difficult than that, add another tablespoon of milk.
Divide the dough in half and pat each half into a 2.5cm-thick disk. Wrap each disk in plastic wrap and chill in the refrigerator for at least one hour and as long as two days. Let dough come to room temperature for 30 minutes before rolling it.