Toss the cheese and cornstarch together in a saucepan.
Add all other ingredients and cook over medium heat, whisking often until the cheese is melted and smooth.
While hot it will have a sauce-like consistency (perfect for pouring over nachos). As it cools it will thicken and become a dip-like consistency. Whisk occasionally to mix in the skin that forms on the top.
Stir in additional evaporated milk or regular milk to achieve the desired consistency if you want to use it as a pourable sauce.