In a medium bowl, whisk together the egg yolks & egg. Stir together the remaining sugar & cornstarch; then stir them into the egg until smooth. When the milk comes to a boil, drizzle it into the bowl in a thin stream while mixing so that you don’t cook the eggs. Return the mixture to the saucepan; slowly bring to a boil, stirring constantly so the eggs don’t curdle or scorch on the bottom.