Preheat the oven to 425°F.
Place the unsalted butter and whole milk in a large saucepan.
Set the saucepan over medium heat.
Bring the milk and butter mixture to a boil, stirring occasionally.
While the milk mixture is heating, place the eggs, granulated sugar, and cornstarch in a large mixing bowl.
Beat the egg mixture with an electric mixer for 4 to 5 minutes, or until smooth and well combined.
Gradually add the hot milk and butter mixture to the beaten egg mixture in several small additions.
Beat well after each addition to temper the eggs and prevent curdling.
Once the hot milk mixture has been fully incorporated, transfer the warm mixture back to the saucepan.
Cook over medium-low heat, stirring constantly, until the filling thickens.
Continue cooking for approximately 10 to 12 minutes, or until the mixture reaches a thick, creamy consistency.
Remove the saucepan from the heat.
Add the vanilla extract.
Stir until fully combined.
Transfer the hot cream filling to a large bowl.
Cover the filling with plastic wrap, pressing the wrap directly onto the surface to prevent a skin from forming.
Refrigerate the filling for at least 2 hours, or until fully chilled.
While the filling chills, place the thawed pie crust into a pie plate.
Press the crust evenly into the bottom and up the sides of the pie plate.
Line the crust with parchment paper and fill it with pie weights.
Bake the crust in the preheated oven for 10 to 15 minutes.
Remove the pie weights and parchment paper.
Return the crust to the oven and bake for an additional 10 to 15 minutes, or until golden and fully baked.
Remove the crust from the oven and allow it to cool completely to room temperature.
Place the cold heavy cream and granulated sugar in a mixing bowl.
Beat with an electric mixer until stiff peaks form.
Remove the chilled cream filling from the refrigerator.
Stir in the flaked coconut until evenly distributed.
Spoon the coconut cream filling into the cooled baked pie crust.
Spread the filling evenly with a spatula.
Top the filling with the prepared whipped cream.
Spread or pipe the whipped cream evenly over the surface of the pie.
Sprinkle toasted coconut over the whipped cream to taste.
Refrigerate the assembled pie for at least 1 hour before serving.
Slice and serve chilled.