In a large saucepan away from heat, combine the sugar, cornstarch and salt. Add the egg yolks and stir to make a thick, yellow paste, then gradually whisk in the half and half.
Put the saucepan over medium heat and whisk constantly until mixture begins to boil and thicken. When mixture thickens and boils, continue whisking for 1 minute. Remove from heat and whisk in the butter. Let cool slightly, then stir in the vanilla extract, coconut extract and 2/3 cup coconut.
Let filling cool, then transfer it to the tart shell, spreading to the edges. Cover with a piece of plastic wrap and refrigerate until cold. Spread whipped cream over the top and sprinkle with reserved coconut. To toast the reserved coconut, bake it on a foil lined tray at 350 just until edges start to brown, then mix it all up on the pan. Let cool.