Bake pie crust and let cool.
Toast 1/2 cup of the coconut flakes under a broiler. Be careful - they burn very quickly.
Heat the coconut milk, sugar, salt and vanilla bean in a medium saucepan over medium heat. In a bowl, whisk together the egg yolks and corn starch. Once the cream is hot, remove the vanilla bean, scraping out any remaining seeds and returning them to the cream. Add 1/2 cup of the hot cream slowly to the yolks, whisking as you add. Then pour the yolk mixture into the pot of hot cream and whisk. Continue to whisk with heat on medium-high for 3 more minutes. The mixture will turn thick and bubble. You need to continue to whisk for the full 3 minutes or the pastry cream will separate once it is cool. After the 3 minutes, whisk in the butter. Add the coconut flakes. Pour into a shallow dish to cool.
Cover with plastic wrap pressed right against the pastry cream. This will prevent a thick skin from forming on the surface. Refrigerate for at least an hour or freeze for 30 minutes. Once it is cold, stir the pastry cream to loosen.
Beat whipped cream and sugar until whipped cream reaches medium peaks. Fold about 1/4 of the whipped cream into the pasty cream.
Spoon pastry cream into the cooled pie crust, then top with remaining whipped cream. Sprinkle with toasted coconut.