In a large suace pan, stir in 3 cups (750 ml) milk with sugar. Set over medium-high heat, stir and bring to a simmer.
Place remaining milk in a medium bowl. Whisk in cornstarch until dissolved. Once milk reachers a simmer, add the cornstarch mixture and whisk continually.
Bring to a rolling boil, stirring constantly until mixture thickens, 1-2 minutes.
Remove from heat, stir in vanilla.
Pour into a bowl or individual serving dishes.
To prevent a skin from forming, place plastic wrap on surface of pudding.
Refrigerate for at least 4 hours, or until set.
Discard plastic wrap. Sprinkle with raisins and cinnamon or your favourite toppings.
