Meanwhile, in large heavy saucepan, mix 1/2 cup sugar and the cornstarch. In small bowl, beat half-and-half and egg yolks with whisk. Gradually add egg mixture to sugar mixture; heat to boiling over medium heat, stirring constantly. Boil 1 minute; remove from heat. Stir in butter, 1 cup coconut and 1 teaspoon of the vanilla. Cover with plastic wrap, placing plastic wrap directly on custard; let stand 30 minutes. Spoon custard into cooled baked shell. Cover; refrigerate 30 minutes or until set.