In 2-quart heavy saucepan, stir eggs, granulated sugar and salt until well mixed. Gradually stir in milk. Cook over medium heat 10 to 15 minutes, stirring constantly, until mixture just coats a metal spoon; remove from heat. Stir in 1 teaspoon vanilla. Place saucepan in cold water until custard is cool. (If custard curdles, beat vigorously with hand beater until smooth.) Cover and refrigerate at least 2 hours but no longer than 24 hours.