Whisk the sugar, vanilla and egg yolksin a medium bowl. Gradually strain in and whisk about half of the warm milk mixture into the eggs. Then, while whisking constantly, add the warmed eggs to the remaining milk mixture.
Return to the heat and cook the gelato base, stirring constantly with a wooden spoon, until thick and it coats a spoon, about 10 minutes. Transfer the mixture into a bowl set over an ice bath to stop the cooking and bring down the temperature.
Fold in desired mix-ins once the gelato has finished spinning in the machine.Transfer to a container and freeze until solid and ready to serve.