Have your baked pie crust ready. Prepare filling.
In a heavy non-stick 3 quart saucepan, stir together the sugar, cornstarch and salt.
In a bowl, whisk the egg yolks with the milk, then whisk the egg yolk mixture into the cornstarch mixture.
Place the saucepan over medium heat and cook until mixture begins to boil, whisking often. When mixture boils, boil and whisk constantly for 3 minutes. Remove from heat and stir in butter, vanilla and coconut. Immediately pour the filling into the baked pie crust, press a piece of waxed paper or plastic wrap onto the surface and let cool for 20 minutes at room temperature.
Place in refrigerator to chill for 3 hours or more. At some point, toast the extra coconut (see note at bottom)
When the pie has chilled, prepare whipped cream topping. In a large bowl, beat cream until soft peaks form. Add the powdered sugar and vanilla beat until peaks are stiff. Spread over top of pie. Sprinkle with toasted, cooled coconut.
To toast coconut, lay it on a cookie sheet and bake at 375 degrees for about 5 minutes or until edges turn brown. Stir every 2 minutes or so.