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 over medium heat and bring to a simmer, stirring occasionally.
While whisking constantly, slowly drizzle some of the hot milk into the egg yolks. 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 cook, whisking constantly, until thickened and coats the back of a spoon, about 2-3 minutes.
Remove from heat. Mix in the butter, vanilla extract and coconut extract until butter melts. Stir in ¾ cup of the toasted coconut (reserve the rest for topping). Refrigerate filling for 10 minutes, stirring often.
Pour filling into a cooled, baked pie crust. Cover surface with plastic wrap or parchment to prevent a skin. Refrigerate for at least 4 hours, or up to 2 days.