In a large saute chef or a saucier, whisk the cornstarch, sugar, and powdered milk together while adding a pinch of salt. You should continue mixing until the mix is all smooth and well-combined with no clumping.
Once all clumps are gone, gradually add about 1 2/3 cups of the whole milk, and gently whisk it to combine.
Cook the mixture over medium heat while whisking until it starts to simmer.
Once the mix starts to boil, whisk it exactly for one minute to fully hydrate the cornstarch. You can use a timer for that.
After that one minute, transfer the mixture to a relatively large bowl, and add the remainder of the milk and vanilla extract to the mix while whisking.
Cover the mix and refrigerate it until it’s cold and thick, which usually takes about 3 hours if you use a glass bowl or 2 hours if you’re using a stainless steel one.
Chill a spatula and a suitable sized container in the freezer while you churn the mix in your ice cream maker according to the directions of your model.
When the ice milk looks thick and smooth but still in a liquid state, shut off the machine and scrape it out with the cold spatula into the container.
if you don’t have an ice maker, you can simply pour the mix into a freezer container and manually stir the mixture every hour to keep it smooth and fluffy until the ice starts to form. This should take 8 hours.