Place your butter,chopped onion and chopped garlic in a stock pot, saute until translucent. Add your carrots, and celery, and continue to saute, for 5 minutes.
Add your flour to the vegetables to create a roux. Add your Chicken Broth and bring to a slow boil to allow the broth to thicken. Add your chopped potato to your soup and cook for about 15 minutes.
Reduce the heat to low and add your milk and corn to the soup,
The final step is to add your shredded chicken to the soup and season.