While the meatballs are cooking in the oven, begin making the soup portion. In a large pot, over medium-high heat, add 1 tbsp of olive oil.
Add the pancetta, carrots, celery, and onion. Cook until the pancetta is slightly crisp and the veggies are tender, about 5-7 minutes.
Add the garlic and zucchini. Cook until the zucchini has slightly softened and the garlic is fragrant, about 2 minutes.
Now add the tomato paste, salt, pepper, crushed red pepper flakes, Italian seasoning, and fennel seeds. Stir, coating the veggies in the spices. Cook for 2 minutes until the tomato paste is no longer raw.
Add the beef broth, fire-roasted tomatoes, white beans, and parmesan rind (if using). Add the meatballs back to the skillet as well.
Bring the soup to a boil, then lower the heat to low, and cover. Cook for 30 minutes until the veggies are tender and the soup has slightly reduced. While your soup is simmering, cook your pasta according to package directions until al dente.
After 30 minutes, retrieve the parmesan rind if applicable. Then add the spinach, cooked pasta, and 1/4 cup of grated parmesan cheese. Stir until the spinach has wilted and is incorporated.
Ladle the soup into bowls and top with a little extra parmesan cheese. Enjoy!
Note: If you have leftover soup, the pasta will continue to absorb the liquid. Simply add a little more beef broth to the leftovers and gently reheat in a pot or in the microwave.