How to Make It
Combine 1/4 cup milk and flour in a saucepan; stir with a whisk. Stir in remaining 3/4 cup milk and salt; bring to a boil over medium heat, stirring frequently. Reduce heat to low; simmer 2 minutes or until slightly thickened, stirring constantly. Remove from heat. Stir in cheese and pepper, stirring until cheese melts.
Tips: Remove from heat, then stir in the cheese to ensure that the sauce doesn't curdle. The flour helps stabilize the dairy mixture, but if it's boiled after the cheese is added, the sauce will separate or curdle.