Ingredients
- 3 tablespoons butter
- 2 large onions, sliced
- 3 14 1/2-ounce cans beef broth
- 1 14 1/2-ounce can low-salt chicken broth
- 1 celery stalk, halved crosswise
- 2 bay leaves
- 4 sourdough bread slices, toasted
- 1 cup grated Swiss cheese
Directions
- Melt butter in heavy large saucepan over medium heat. Add onions and cook until golden brown, stirring frequently, about 20 minutes. Mix in both broths, celery and bay leaves. Simmer 35 minutes. Discard celery and bay leaves. Season to taste with pepper. (Can be prepared 2 days ahead. Refrigerate. Rewarm soup before continuing.)
- Preheat broiler. Ladle soup into broilerproof bowls. Top each bowl of soup with slice of toast and grated cheese. Broil until cheese melts and bubbles.
