Roll out dough into a 13-inch round on a lightly floured surface with a lightly floured rolling pin, then fit into tart pan. Trim excess dough. Chill until firm, about 30 minutes.
Meanwhile, preheat oven to 375°F with rack in middle.
Lightly prick bottom of shell all over with a fork, then line with foil and fill with pie weights.
Bake until edge is pale golden and side is set, 20 to 30 minutes. Carefully remove weights and foil and bake shell until deep golden all over, 10 to 18 minutes more.
Whisk together milk, eggs, yolk, confectioners sugar, and salt in a large bowl until smooth, then stir in coconut.
Pour filling into hot tart shell and spread evenly with a fork.
Bake until top is golden, about 35 minutes. Cool in pan on a rack 5 minutes, then remove side of pan and cool tart to room temperature, about 2 hours.
· Tart shell can be baked 1 day ahead and kept, wrapped in plastic wrap, at room temperature.· Tart is best the day it is baked but can be baked 1 day ahead and chilled (once cool), loosely covered with foil. Reheat in a 350°F oven, uncovered, until pastry is crisp, 10 to 15 minutes.
