1 medium yellow onion, chopped
2 tablespoons olive oil
4 cloves garlic, minced
4 carrots, peeled and sliced
4 stalks celery, sliced
32 ounces vegetable broth
1 quart whole tomatoes, crushed or 28 ounces crushed tomatoes (canned)
2 teaspoons fresh thyme leaves or 1 teaspoon dried
2-3 teaspoons salt or more if needed
Freshly ground black pepper
2 bay leaves
1 - 15 ounce can white kidney beans, drained and rinsed
2 zucchini, sliced
8 ounces cooked ditalini pasta
2 cups spinach or Swiss chard (optional)
Grated Parmesan cheese (optional)