Blue Cheese Soup with Potatoes and Walnuts Recipe

Finely dice the onion and potato. Thinly slice the celery and mince the garlic. Over medium heat, melt the butter in a 2 or 3 quart saucepan. Without browning, cook the onion, garlic, celery and potato until the onion is soft, 5 - 10 minutes. Stir in broth and milk. Add crumbled blue cheese, reserving 1 tablespoon for garnish, and walnuts. Simmer until all vegetables are tender, about 10 minutes. Stir in the yogurt and continue cooking for 2 or 3 minutes, but do not boil. Sprinkle on reserved cheese, taste for seasoning, add salt and pepper to taste. Serve hot.