Heat olive oil in a large Dutch oven over medium heat. Add diced onion, carrots, and celery. Cook for 8-10 minutes, stirring occasionally, until vegetables are softened and onion is translucent. Pro tip: This trio of vegetables is called 'soffritto' in Italian cooking and forms the flavor foundation of many Italian soups.

Add minced garlic and cook for another minute until fragrant. Stir in tomato paste and cook for 2 minutes, allowing it to caramelize slightly and deepen in color. Pro tip: Cooking the tomato paste removes its raw taste and concentrates the flavor.

Add diced tomatoes with their juice, breaking them up with your spoon. Pour in the vegetable broth and add bay leaf, oregano, and basil. Bring to a boil, then reduce heat and simmer for 10 minutes. Pro tip: If using a Parmesan rind, add it now for extra umami flavor.

Add diced potatoes and green beans to the pot. Simmer for 15 minutes, or until potatoes are fork-tender but still hold their shape. Pro tip: Cut potatoes into uniform pieces to ensure even cooking.

Stir in the zucchini and cannellini beans. Continue cooking for 8-10 minutes until zucchini is tender but not mushy. Pro tip: Add zucchini later in the cooking process to prevent it from becoming overcooked and losing its texture.

Add pasta to the soup and cook according to package directions until al dente, usually 8-10 minutes. Stir occasionally to prevent sticking. Pro tip: If you plan to store leftovers, consider cooking pasta separately and adding it to individual bowls to prevent it from getting mushy.

Remove bay leaf and stir in chopped spinach. Cook for 2-3 minutes until spinach is wilted. Season with salt and pepper to taste. Pro tip: Taste and adjust seasoning at the end – you may need more salt depending on the sodium content of your broth.

Remove from heat and stir in fresh chopped parsley. Ladle into bowls and garnish with additional fresh herbs or grated Parmesan cheese if desired. Serve immediately while hot. Pro tip: Let the soup rest for 5 minutes before serving to allow flavors to meld together.