In a food processor, pulse the flour with the sugar and salt. Add the butter and pulse until the mixture resembles coarse meal. Add the egg yolk and pulse until a crumbly dough forms.
Turn the dough out onto a lightly floured surface; knead 3 times until it just comes together. Pat the dough into two disks. Wrap in plastic and refrigerate for at least 30 minutes or overnight.
On a lightly floured work surface, roll each disk out to a 12-inch round. Fit each round into a 9-inch glass pie plate. Trim the overhang to 1 inch and fold the edge under itself, then crimp decoratively. Refrigerate until firm.
Make Ahead: The dough can be frozen for 1 month. The pie shells can be refrigerated overnight.