Toast 3/4 cup coconut in a dry skillet over medium-low heat for 4 to 5 minutes until patchy golden.
Whisk the milk, granulated sugar, cornstarch, salt and egg yolks in a saucepan and cook over medium heat until boiling and thick.
Boil for 1 minute while whisking, remove from the heat, and stir in the butter, vanilla, untoasted coconut and half the toasted coconut.
Pour the filling into the crust, press parchment on the surface, and refrigerate for 5 hours.
Beat cream and powdered sugar to soft peaks, spread over pie and scatter remaining toasted coconut evenly over cream.