In a Dutch oven or soup pot. Add the chicken stock and place over medium heat. Bring the soup to a simmer, add the chicken breasts and let boil.
Meanwhile, chop the onion, celery, carrots and potatoes. Add to soup.
Grate 2 cloves of garlic into soup.
Reduce the heat to low; cover and let simmer for 20 minutes.
Add pastini and cook for another 10 minutes, uncovered.
Add salt and pepper to taste. Taste the soup, the stock has salt so you will need to adjust the amount of salt accordingly. I usually add 1 tbsp. but this varies depending on the type of stock you use.
Turn off heat and add parsley.