In a saucepan, add the cornstarch and the milk, stir until dissolved.
Add another 500ml of milk and the butter, turn on the heat to medium-low and stir nonstop until a smooth and uniform mixture forms.
Once you’ve done that, add the grated cheese and stir well until combined.
Add the salt and stir again until incorporated.
Transfer this whole mixture to a milk carton box with a cut top.
Cover with plastic wrap and take it to the fridge, let it chill for at least two hours.
Unmold and serve.