Trim, peel and dice the carrots, celery, zucchini and potato so that each yields about 1 cup diced. Finely chop the onion and mince the garlic. Rinse and drain the cannellini beans; roughly chop the spinach if leaves are large.

Sauté aromatics

In a large heavy pot or Dutch oven, heat 2 tbs olive oil over medium heat until shimmering. Add the chopped onion, carrots and celery and cook, stirring occasionally, until softened and translucent, about 6–8 minutes. Add the minced garlic and cook 1 minute more until fragrant.

Add vegetables and tomatoes

Stir in the diced zucchini and potato and cook 3–4 minutes to begin softening. Pour in the canned diced tomatoes with their juices, scraping any browned bits from the bottom of the pot.

Simmer with broth and herbs

Add the 6 cups of broth, thyme and bay leaf. Increase heat to bring to a gentle boil, then reduce heat to maintain a simmer. Cover partially and simmer until the potato is nearly tender, about 12–15 minutes.

Cook pasta and beans

Add the small pasta and drained cannellini beans to the simmering soup. Continue cooking uncovered, stirring occasionally, until the pasta is al dente and the vegetables are tender, about 8–10 minutes (follow the pasta package guidance for timing). If the soup becomes too thick, add 1/2 cup water or broth at a time to reach desired consistency.

Finish soup

Remove the bay leaf. Stir in the chopped spinach and let wilt for 1–2 minutes. Season with 1 tsp salt and 1 tsp freshly ground black pepper; adjust to taste. Remove from heat and let rest 5 minutes so flavors meld.

Serve

Ladle soup into bowls and sprinkle each serving with about 1 tbs grated Parmesan. Offer additional Parmesan and freshly ground pepper at the table.

Garlic-Parmesan Croutons (optional)

Make croutons

Preheat oven to 375°F (190°C). Toss the cubed bread with melted butter, garlic powder, grated Parmesan and 1 tsp salt until evenly coated. Spread in a single layer on a baking sheet and bake 10–12 minutes, tossing once, until crisp and golden. Cool slightly and sprinkle over individual bowls of minestrone if desired.