Baked Potato Soup

Ingredients : 

2 large potatoes, baked, peeled and cubed
1 cup onion and celery, chopped
3 tablespoons butter or olive oil
4 cups milk
3 teaspoons salt and pepper
3 tablespoons flour
1 cup grated cheddar cheese
? cup bacon bits
? cup light sour cream
Chopped fresh chives to taste

Preparation :

Saut? the onion and celery in a tablespoon of butter or olive oil until tender.
Combine this mixture with the milk and salt and pepper in a large saucepan, stir occasionally and bring to the boil.
In a separate saucepan, heat two tablespoons of butter or oil until melted, whisk in the flour then cook for 3 minutes. Whisk this into the milk mixture and cook until thickened, stirring constantly.
Add the potatoes, mix well and warm until the soup is heated through.
Top each serving with cheddar cheese, grilled bacon bits, sour cream and chives."