Heat 4 tablespoons oil in heavy large skillet over medium-high heat. Add bread cubes and garlic and saute until bread is light golden, about 4 minutes. Add wine, then broth and saffron; bring to boil. Reduce heat, cover and simmer 25 minutes. Puree soup in blender. Return soup to saucepan. Season with salt.

Preheat oven to 350F. Arrange French bread slices on cookie sheet. Brush with remaining 1 tablespoon oil. Bake until lightly toasted, about 8 minutes. Sprinkle cheese over croutons. Transfer cookie sheet to broiler; broil croutons until cheese melts. Place 2 croutons in each bowl. Bring soup to simmer. Ladle over croutons. Sprinkle with chives and a few saffron threads and serve.