In a medium, heavy-bottom saucepan set over low heat, combine cheese and cornstarch. Toss to combine.
8 ounces extra sharp Cheddar cheese, 4 ounces Pepper Jack cheese, 1½ tablespoons cornstarch
Add evaporated milk and hot sauce and whisk constantly until cheese is melted. Continue whisking about 5 minutes or until the cheese is bubbly and has thickened.
12 ounces evaporated milk, 2 teaspoons hot sauce
If cheese has thickened too much, add additional evaporated milk.