In a saucepan, toss cheese and cornstarch together until cheese is evenly coated.
Stir in evaporated milk, salt, pepper, garlic powder and cayenne pepper and cook over medium heat until cheese is melted, whisking often. Cheese sauce will be done cooking in about 5 minutes.
While hot, sauce is more liquid, like nacho cheese. When it cools down, it will be a thicker, dip consistency.