Cream Of Chicken Soup

1 cup diced celery
1 cup diced onion
1/2 cup diced carrot
2 tablespoons chopped parsley
1 tablespoon minced garlic
3/4 cup (1 1/2 sticks) butter, divided
8 cups chicken stock or broth (see note)
2 cups heavy cream
4 cups frozen mixed vegetables
2 cups cubed cooked potatoes (cut into 1/2-inch pieces)
1/2 teaspoon salt or to taste
1/2 teaspoon ground black pepper or to taste
1/4 teaspoon dried thyme leaves
1/4 teaspoon crushed dried rosemary
1/4 teaspoon rubbed sage
1 tablespoon granulated sugar
1/2 cup all-purpose flour
2 cups chopped cooked chicken (see note)

In a large pot, saute celery, onion, carrot, parsley and garlic in 1/4 cup butter until tender, about 10 minutes.

Add broth, cream, mixed vegetables, potatoes, salt, pepper, thyme, rosemary, sage and sugar.

Bring to a boil, reduce heat and simmer 20 minutes.

Melt remaining 1/2 cup butter; whisk in flour to make a roux. Whisk the roux into the soup; simmer 10 minutes. (For thicker soup, add more roux, made of equal parts flour and melted butter.) Add chicken; cook until heated through.

Note: Poach 2 skinless, boneless chicken breast halves to yield about 2 cups of chopped chicken. Use the cooking liquid for part of the stock.