In small bowl, beat remaining 1/2 cup milk and the cornstarch with whisk until no lumps remain. Stir cornstarch mixture with whisk into cereal-milk mixture until combined. In another bowl (or the cornstarch bowl), beat egg yolks, 1/3 cup granulated sugar and 1/8 teaspoon salt with whisk until well combined and yolks begin to get pale and thick. Ladle a bit of the warm cereal-milk mixture into egg yolk mixture until combined. With rubber spatula, scrape egg yolk mixture into cereal-milk mixture in saucepan. Return saucepan to heat. Cook over medium-low heat, stirring constantly and making sure to scrape bottom and side of saucepan, until pudding thickens, whisk or spoon leaves tracks on surface of pudding, and mixture coats back of spoon.