Cream of Chicken and Broccoli Soup

2 tbs. Butter
1/2 c. chopped onion
1 c. sliced carrots
1 c. chopped celery
1 c. chicken stock (liquid from cooking chicken)
1 bunch broccoli (1 bag broccoli florettes)
2 cooked and diced chicken breasts
4 tbs. flour
2 c. milk
2 c. half & half
2 tsp. salt

Melt butter and add onions. Cook until translucent. Add carrots, celery and chicken stock and cover and simmer for 10 minutes. Add broccoli and cook 10 minutes. Add chicken. Mix the flour in with a little of the milk and add the flour, milk and half & half. Stir in the salt and cook until thickened.