How to Make It
Heat a large Dutch oven over medium-high. Add sausage, and cook, stirring to crumble, until no longer pink, 6 to 8 minutes. Drain, leaving 1 tablespoon of drippings with sausage in Dutch oven. Add onion, celery, fennel, garlic, salt, red pepper, and 1/2 teaspoon of the black pepper. Cook, stirring often, until vegetables have softened, about 5 minutes. Add white wine, and scrape any browned bits from the bottom of the Dutch oven. Stir in chicken stock, beans, and tomatoes; bring to a boil. Reduce heat to medium-low, and simmer 10 minutes.
Preheat broiler with oven rack 6 inches from heat. Place baguette slices on a rimmed baking sheet, and brush 1 side of each piece with olive oil. Sprinkle evenly with cheese and remaining 1/2 teaspoon pepper. Broil until cheese is melted and beginning to brown, 1 to 2 minutes. Remove from oven.
Ladle 1 1/2 cups soup into each of 8 bowls; sprinkle with chopped rosemary, and serve with toasts.