Preparation Melt butter in heavy large pot over medium-high heat. Add onions and sauté until dark brown but not burned, stirring occasionally, about 30 minutes. Add broth, wine, and mustard and bring to boil. Reduce heat to medium and simmer until flavors blend, about 15 minutes. Add brandy to taste and simmer 5 minutes. Season soup with salt and pepper. Meanwhile, preheat broiler. Arrange bread on baking sheet. Broil until beginning to color, about 1 minute. Mound cheese and ham on bread; sprinkle with pepper. Broil until cheese melts, turning sheet for even cooking, about 2 minutes. Ladle soup into deep bowls. Top each with 3 croutons and serve.
Preparation Melt butter in heavy large pot over medium-high heat. Add onions and sauté until dark brown but not burned, stirring occasionally, about 30 minutes. Add broth, wine, and mustard and bring to boil. Reduce heat to medium and simmer until flavors blend, about 15 minutes. Add brandy to taste and simmer 5 minutes. Season soup with salt and pepper. Meanwhile, preheat broiler. Arrange bread on baking sheet. Broil until beginning to color, about 1 minute. Mound cheese and ham on bread; sprinkle with pepper. Broil until cheese melts, turning sheet for even cooking, about 2 minutes. Ladle soup into deep bowls. Top each with 3 croutons and serve.