To make the pie crust: Combine the water and vinegar and refrigerate to make sure it’s extra chilled. Keeping everything cold and working quickly are the keys to flaky pie crust.
Place the flour and salt in a mixing bowl and give it a good stir. Add the butter cubes, and using your fingers, a fork, or a pastry blender, break the butter up into the flour. You should end up with a coarse, gravel-like mixture. Add the water and vinegar mixture about a tablespoon at a time, stirring with a fork and your hands until the dough comes together.
Cut the dough into two equal pieces, and shape them into round, flat disks. Wrap in plastic wrap and refrigerate for at least 30 minutes. This dough actually became hard as a rock in the refrigerator when I left it in overnight, and needed to thaw on the counter for a while, so you might not want to leave it in the refrigerator much longer than 30 minutes.
You only need half of the dough for this pie crust, but I always make a full batch. That way I can keep half in the freezer and be able to make another pie, or a quiche, without as much work.
To partially bake the pie crust, roll out one disk on a lightly floured surface to a circle about 1/8 of an inch thick. Wrap the crust around your rolling pin to transfer to a 9-inch pie plate. Carefully stretch the dough into the plate, pressing gently into the corners. Trim and crimp the edges, and place it in the refrigerator.
Preheat the oven to 325°F Line the pie shell with parchment paper, and fill the pie sheet with pie weights or dried beans, then bake for about 20 minutes, or until the dough is dried, but not brown. Scoop out the pie weights and let the shell cool.
To make the filling: Preheat the oven to 350°F Spread the coconut out on a baking sheet and toast for about 5 minutes, stirring once or twice. It’ll burn easily, so keep an eye on it. Once it’s golden brown, transfer the coconut to a plate to cool. Scatter all but 2 tablespoons of the coconut on the bottom of the partially baked pie shell.
In a mixing bowl, whisk together the whole eggs, egg yolks, and vanilla. Gradually add the sugar and coconut milk, mixing until completely blended. Whisk in the heavy cream and the half and half, but don’t beat too vigorously, as you don’t want the custard to have bubbles. Gently pour the mixture into the pie shell over the toasted coconut.
Bake the pie in the middle of the oven for 55 to 60 minutes. The filling will puff up around the edges, and the center should be firm. Remove from the oven and let cool completely, then cover and refrigerate until chilled.
To make the whipped cream topping: Whip the cream with an electric mixer or stand mixer at medium speed until soft peaks form. Gradually beat in the sugar and vanilla and continue beating until stiff peaks form.
Remove the chilled pie from the refrigerator, and mound the whipped cream on top, spreading it to the edges to make a slightly domed shaped. Garnish with the remaining toasted coconut, and serve chilled.