Add the cornstarch to the ½ c of milk and stir until the cornstarch is well incorporated. Set aside.
Pudding Mix
Add the 3 c of milk to the sauce pot along with the salt and sweetener. I used Whole Earth monk fruit with erythritol which was a 1:1 equivalent to sugar. If you use Splenda or erythritol use the amount that will be equivalent to ⅓ of sugar.
Heat the milk, salt and sweetener on medium heat until it is warm.
While stirring, add the cornstarch slurry to the pudding mix. Continue to stir constantly as you cook the mixture on medium heat.
When the mixture begins to boil, lower the heat and continue to cook for another 1 - 2 min while constantly stirring. You are looking for the mixture to thicken and coat the back of a spoon.
Remove the pudding mixture from the heat.
Add the vanilla to the pudding and stir until it is thoroughly mixed in.
Place a strainer into a large glass mixing bowl. Pour the pudding into the strainer and push it through into the bowl. This will remove any lumps.
Place plastic wrap over the pudding, pushing it down into contact with the surface of the pudding. This will prevent a film from forming.
Put the pudding in a cool place and let it cool to room temperature. I put mine out in the garage.
As soon as it is at room temperature, place it into the refrigerator to chill.
Once it is chilled, remove it from the refrigerator, remove the plastic wrap and stir it up. You can serve it for dessert or use it as an ingredient to build another dessert.