For best results, use freshly shredded cheese rather than pre-shredded varieties, which contain anti-caking agents that can prevent smooth melting.
To store, allow the soup to cool completely before refrigerating in an airtight container for up to 3 days. Reheat gently on the stove, adding a splash of milk if the consistency has thickened too much.
For a vegetarian version, substitute the chicken broth with vegetable broth.
Garnish with fresh chives or a sprinkle of black pepper before serving.