How to Make It
Stir together flour, sugar, and salt in bowl of a stand mixer fitted with the paddle attachment. Add butter; beat on low speed until flour holds together when pinched and there are pecan-size lumps of butter throughout, about 45 seconds. Whisk together milk and egg yolk in a small bowl; add to flour mixture. Beat on low speed just until mixture barely comes together, about 30 seconds. (Dough will be very shaggy.)
Dump dough onto a clean work surface, and gather it into a tight mound. Using palm of hand, smear dough on work surface, piece by piece, until most butter chunks are smeared into dough and dough comes together. Gather dough into a tight mound. Wrap with plastic wrap; press down to shape into a 1-inch-thick disk. Refrigerate dough disk at least 1 hour or up to 4 days.
Unwrap dough; roll out into a 12-inch circle on a well-floured work surface. Place dough inside a 9-inch pie plate, and trim edges to leave a 1/2-inch overhang. Crimp edges. Refrigerate pie shell, uncovered, at least 30 minutes or up to 4 hours.
Preheat oven to 350°F. Line pie shell with parchment paper, and fill with pie weights or dried beans. Bake in preheated oven until pie shell sides are light brown, 35 to 40 minutes. Transfer pie shell to a wire rack; let cool completely with pie weights still in shell, about 1 hour. Once cool, remove weights and parchment. Pie shell can be stored, uncovered, at room temperature up to 4 hours.