Combine 2 1/2 cups milk, sugar, and corn syrup in a saucepan.

Cook over medium heat, stirring frequently, until the mixture begins to steam, ensuring it does not boil.

In a separate bowl, mix the remaining milk, milk powder, cornstarch, salt, and vanilla extract until smooth and the powders are dissolved.

Add the cornstarch mixture to the saucepan and bring to a boil over low heat, stirring constantly.

Whisk the mixture until smooth and simmer over very low heat for 2 minutes, stirring constantly, until thickened.

If the mixture is lumpy, strain it through a sieve.

Transfer the hot liquid to a storage container and cover the surface with plastic wrap to prevent skin formation.

Refrigerate uncovered until completely chilled (below 40°F).

Freeze in an ice cream maker according to manufacturer's instructions.

Serve immediately for a soft gelato, or transfer to an airtight container and freeze until hard.

If frozen solid, allow the gelato to sit at room temperature for 15 minutes before serving.