Combine 1/2 cup sugar and cornstarch in a large saucepan.
Whisk together half-and-half and egg yolks. Gradually add to the sugar mixture, whisking constantly.
Boil the mixture 4-5 minutes while whisking constantly. Don't stop whisking as the mixture can burn very easily. Don't walk away from the mixture at this point.
Remove from heat.
Stir in butter, coconut shreds, and vanilla.
Place plastic wrap directly over the filling (so it's touching the mixturand let the custard sit for about 30 minutes. The plastic will prevent the top layer from hardening.
Pour the mixture into the prepared and baked shortbread cookie pie crust and cover.
Keep it in the refrigerator for an hour (or more!) before serving so it can set.
Top with homemade whipped cream and toasted coconut!
Notes
Make sure the pie mixture has a thicker texture before removing it from the heat.Let the pie set for at least 2 hours, probably more, in the refrigerator. Overnight is usually best.Serve this in any pre-baked pie crust you like!