Cool leftovers completely, then refrigerate in an airtight container for up to 3 to 4 days. Reheat gently on the stove over medium-low heat, adding a splash of chicken stock or water if the soup has thickened. Leftover rotisserie chicken works perfectly here; to use raw chicken, poach two large breasts in the simmering stock in step 4 until they reach 165°F, then shred and add in step 5. For extra greens, stir in 2 cups of baby spinach or chopped kale during the last 2 minutes of cooking, right before adding the cream.