In a bowl, combine sugar, cornstarch, and salt; set aside. Melt butter in a heavy 3-quart saucepan over low heat. Stir in water and the sugar and cornstarch mixture, then stir in the beaten eggs. Cook, stirring, over low heat until thickened and smooth. Stir in vanilla. Cool, stirring occasionally. Pour into cooled piecrust and chill until firm.
Garnish with sweetened whipped cream and milk chocolate curls, if desired.
Calories per serving: 376
Fat per serving: 19g