Melt butter in large pot over medium heat.
Cook onion in butter until soft, about 3 minutes.
Stir flour into onion until it makes a smooth paste. Cook 1 minute.
Add broth and poultry seasoning. Increase heat to medium-high.
Add noodles and cook about 10 minutes or until noodles are soft.
Add chicken and milk and heat through.
Season with salt and pepper and serve.