Preheat oven to 350°F. Roll dough into a rectangle, press into a 9x13-inch dish, crimp edges, and prick with fork. Bake 10–12 minutes until golden. Cool.
In a saucepan, whisk milk, coconut milk, egg yolks, sugar, cornstarch, and salt over medium heat until thickened. Do not boil.
Remove from heat. Stir in coconut flakes, vanilla, and coconut extract. Pour into pie crust and smooth top.
Cool filling for 12 minutes, then cover and chill in refrigerator for 3 hours until set.
Beat heavy cream, powdered sugar, and coconut extract until stiff peaks form. Spread over chilled filling.
Sprinkle with toasted coconut and serve.
Notes
Make sure not to boil the filling mixture or it may curdle. Toast coconut by baking at 350°F for 5–7 minutes, stirring once.