Combine the flour and salt, cut in the cold butter until coarse crumbs form, then add ice water gradually until the dough holds together. Shape into a disk, wrap, and chill for at least 30 minutes.

Roll the dough to fit a 9-inch pie plate, crimp the edges, prick the bottom, and chill for 15-20 minutes. Line with parchment and pie weights, bake at 425°F for about 15 minutes, then remove the weights, reduce the oven to 375°F, and bake 10-15 minutes more until lightly golden; cool completely.

Whisk the sugar, cornstarch, and salt in a saucepan. Gradually whisk in the milk and cook over medium heat, whisking constantly, until the mixture is thick and bubbling, generally 6-8 minutes.

Whisk a small amount of the hot milk mixture into the egg yolks to temper them. Return the yolks to the saucepan and cook for 1-2 minutes more, stirring constantly without allowing the custard to boil aggressively.

Remove the custard from the heat and stir in the butter, vanilla, optional coconut extract, and shredded coconut. Pour into the cooled shell, press plastic wrap directly against the surface, and refrigerate for at least 4 hours or overnight.

Whip the cream, powdered sugar, and vanilla to medium-stiff peaks. Spread or pipe it over the chilled pie and finish with toasted coconut before slicing.