Make the Filling: In a large mixing bowl, combine the instant coconut pudding mix with cold whole milk. Whisk with an electric hand mixer for 2-3 minutes until the mixture thickens. Gently fold in the sweetened shredded coconut using a rubber spatula, maintaining a light and fluffy texture throughout the mixture.
Assemble the Pie: Pour the coconut pudding mixture into your pre-made pie crust. Use a spatula to carefully spread it evenly across the base, creating a smooth surface. The filling may still appear soft at this stage, but it will set properly during chilling.
Chill the Pie: Cover the pie loosely with plastic wrap or foil and refrigerate for at least 2-3 hours, preferably overnight. This crucial chilling time allows the pudding to set completely and the coconut flavors to fully develop and meld together into a cohesive custard.
Add the Whipped Topping: Once the pie is fully set, remove from the refrigerator and spread the whipped topping evenly over the surface. For a decorative finish, create swirls with the back of a spoon or use a piping bag with a star tip for a more elegant presentation.
Decorate and Serve: Sprinkle the toasted coconut or crushed cookies over the whipped topping layer. To toast coconut, heat it in a dry skillet over medium heat for 3-5 minutes, stirring constantly until golden brown and fragrant. Slice the finished pie into 8-10 portions and serve chilled.