Heat butter in a large pot over medium heat. Add onion, carrots, celery, garlic. Sauté for 7 minutes. Add flour, oregano, salt and pepper. Stir and cook for 3 minutes.
Add broth and potatoes. Increase heat. Allow soup to boil for 3 minutes. Reduce heat and cover. Allow to simmer for 25 minutes.
Add chicken, half & half and noodles. Cook for 10 months minutes.