Place the zucchini, onion, carrot, ginger, garlic and celery stalk in a saucepan. Cover with water (or broth) and cook until half cooked.
Add chicken fillet to boiling broth and cook for 15 minutes, add salt and pepper. Then remove the fillet and puree the vegetables.
Gradually add grated Parmesan into the soup, stirring until smooth, add butter if desired.
Cut the chicken fillet into cubes and add to the soup.