In a medium bowl, whisk together the egg yolks, cornstarch and ¼ cup of milk.
In a medium heavy-bottomed saucepan, combine the remaining 1 cup milk, canned coconut milk, granulated sugar and salt. Set the mixture over medium heat and bring to a simmer, stirring occasionally.
While whisking constantly, slowly drizzle some of the hot milk into the egg yolks. Do this slowly so you don’t accidentally cook the eggs. Continue whisking until you’ve added about ½ of the hot milk.
Pour the egg-milk mixture into the saucepan over medium-low heat and continue to cook, whisking constantly, until the mixture has thickened and coats the back of a spoon, about 2-3 minutes.
Remove from the heat and mix in the butter, vanilla extract and coconut extract, stirring until butter has melted. Stir in ¾ cup of the toasted coconut (reserve the rest for topping on the finished pie). Refrigerate the coconut filling for 10 minutes, stirring often.
Pour the coconut filling into the cooled, baked pie crust. Place a piece of plastic wrap or parchment paper directly over the surface of the pudding (to prevent a skin from forming), and refrigerate for at least 4 hours, or up to 2 days.