1 Tbs. butter
1 c. or more chopped celery with leaves
1/3 c. thin onion slices
2 c. chicken or vegetable stock
2 c. milk, divided
1 1/2 Tbs. cornstarch
2 Tbs. chopped fresh parsley

Melt butter in saucepan, add celery and onion, and sauté 2 minutes. Add stock; simmer 10 minutes. Strain or purée soup. Return to heat, add 1 1/2 cups of the milk, and bring to a boil. Dissolve cornstarch in remaining 1/2 cup of milk; stir gradually into hot soup. Bring to a boil again; stir and cook about 1 minute. Sprinkle with parsley. Makes 4 cups.

(from Joy of Cooking)