Melt butter in a stock pot over medium heat. Add the carrots, onion, and celery. Cook until the vegetables are softened. Add in the garlic and cook for 1 minute.
Add the chicken broth, salt and pepper, parsley, and cooked chicken. Bring the soup to a boil. Add the shell pasta and reduce to a simmer. Cook about 10-12 minutes, stirring occasionally, until the pasta is tender. Serves 6-8.