In a medium saucepan, whisk together the granulated sugar, cornstarch, and salt until well combined.

Gradually whisk in the whole milk, ensuring that there are no lumps.

Place the saucepan over medium heat and continuously whisk until the mixture starts to thicken and comes to a gentle boil, about 5–7 minutes.

Once boiling, continue to cook for an additional 2 minutes, stirring constantly.

Remove the saucepan from heat and stir in the vanilla extract and unsalted butter until smooth.

Carefully pour the pudding into individual serving cups or bowls.

Let the pudding cool at room temperature for about 10 minutes, then cover with plastic wrap and refrigerate for at least 20 minutes.

Serve chilled, plain or with toppings.