IN a small saucepan, combine the sugar, cornstarch and salt. Stir in milk until smooth. Cook and stir over medium to high heat until thickened and bubbly. Reduce heat; cook and stir 2 min. longer. Remove from the heat. Stir a small amount of hot filling into egg yolks; return all to the pan, stirring constantly. Bring to a gentle boil; cook and stir 2 min longer. Remove from the heat. Gently stir in chopped coconut, butter and vanilla until butter is melted. Pour hot filling into crust.
For the meringue, in a small mixing bowl, beat egg whites and cream of tatar on medium speed until soft peaks form. Gradually beat in sugar, 1 tablespoon at a time, on high until stuff glossy peaks form and sugar is dissolved. Spread evenly over hot filling, sealing edges to crust. Sprinkle with flaked coconut.
Bake at 350 degree F for 12-15 minutes or until the meringue is golden. Cool on wire rack for 1 hr. Refrigerate for at least 3 hrs. before serving. Refrigerate leftovers.