Preheat your oven to 375°F (190°C). Roll out your pie crust and fit it into a 9-inch pie pan. Prick the bottom with a fork and bake for about 20 minutes or until golden brown. Let it cool completely.

Preheat your oven to 325°F (160°C). Spread shredded coconut on a baking sheet and toast for 5-8 minutes until golden brown, stirring occasionally.

In a medium saucepan over medium heat, combine milk, coconut milk, sugar, cornstarch, and salt. Whisk until the mixture thickens and bubbles, about 5-7 minutes.

Whisk the egg yolks in a separate bowl. Slowly add a small amount of the hot milk mixture to the yolks while whisking to avoid curdling. Pour the egg mixture back into the saucepan.

Return the saucepan to medium heat and stir continuously for 2-3 minutes until the custard thickens. Remove from heat and fold in the toasted coconut, butter, and vanilla.

Pour the warm custard into the cooled pie crust and smooth the top. Cover tightly with plastic wrap and refrigerate for at least 4 hours, or overnight.

Beat heavy cream, powdered sugar, and vanilla in a mixing bowl until soft peaks form. This will be your whipped topping.

Remove the plastic wrap from your chilled pie and spread the whipped topping over the custard. Sprinkle with additional toasted coconut. Slice and serve chilled.