COMBINE sugar and cornstarch in medium saucepan. Stir in evaporated milk and water. Cook over medium heat, stirring constantly, until mixture comes just to a boil. Remove from heat.
PLACE egg in small bowl; stir in small amount of milk mixture. Add to milk mixture; cook, stirring constantly, for 1 minute. Remove from heat. Stir in butter and vanilla extract. Pour into dessert dishes. Refrigerate for 1 hour or until firm. Top with whipped cream.