Think of this recipe as a guide. The soup is excellent as written, but this is the perfect opportunity to use up vegetables in the fridge. This is great eaten straight away and it will keep overnight. The pasta may become softer overtime, but the flavors of the soup will improve.
2 tablespoons extra-virgin olive oil
8 ounces bulk spicy or Italian pork sausage, see note
2 medium bulbs fennel, trimmed and finely chopped
1 medium onion, finely chopped
3 medium carrots, peeled and finely chopped
3 stalks celery, finely chopped
3 garlic cloves, minced
2 medium zucchini or yellow summer squash, finely chopped
1 (15-ounce) can diced tomatoes, with juice
1 (15-ounce) can cannellini beans (white kidney beans)
8 cups low-sodium chicken stock, see how we make chicken stock
1 bay leaf
3 sprigs fresh thyme
3/4 cup small dried pasta such as penne, elbow or orecchiette
1 pound baby spinach (about 4 cups)
Salt and fresh ground black pepper
1/4 cup fresh parsley leaves and tender stems, chopped
Fresh grated Parmesan cheese for serving
Heat the olive oil over medium-low heat in a large, heavy soup pot or Dutch oven and add the fennel, onion, carrots and celery. Cook, stirring, until beginning to soften, about 3 minutes. Stir in 1/2 teaspoon of salt and garlic and cook for 1 minute.
Add zucchini, tomatoes with juice, beans, bay leaf, thyme and the chicken stock, and bring to a simmer. Stir in 1 teaspoon of salt, taste then adjust with more as needed. Add 6 to 7 generous grinds of black pepper. Reduce heat to low and simmer about 20 minutes.
Add pasta and cook until it is tender but not mushy, 8 to 10 minutes. Stir in spinach and parsley and cook until wilted, about 2 minutes. Taste the soup and adjust with more salt and/or pepper. Serve with parmesan cheese on top.