Preheat the oven to 350°F and spray a 9-inch pie dish with nonstick spray.
Roll the pie dough out and place it in the pie dish. Trim and crimp the edges. Place the pie shell in the freezer for 15 to 20 minutes.
When the pie shell is cold and hard, remove it from the freezer and place a sheet of parchment paper inside. Fill the parchment-lined pie with pie weights and bake for 15 minutes, remove pie weights and bake another 10 minutes or until golden brown.
Remove the pie shell from the oven and place it on a cooling rack.
Decrease the oven temperature to 325°F.
While the pie is baking, combine the shredded coconut and the buttermilk in a mixing bowl. Cover the bowl and let the coconut absorb the liquid for 15 minutes.
Stir the cornstarch into the sugar until well incorporated then add it to the bowl with the coconut.
Add the melted butter, eggs, egg yolk, vanilla, almond extract, and salt. Stir well.
Pour the mixture into the warm pie shell and bake for 50 to 60 minutes.
Transfer the pie to a cooling rack and let cool for 4 hours.
Serve at room temperature.
Notes
If you mix the cornstarch with the sugar before whisking it into the liquid, it will blend in smoothly and avoid clumping.
If you can’t find unsweetened coconut shreds, you can substitute it with sweetened coconut and reduce the sugar to 1-1/4 cups.