Cut the bacon into small pieces, add it to a soup pot, and fry until crispy over medium-high heat (about 10 minutes).
Transfer the bacon to a paper towel lined plate. Leave about 2-3 tablespoons of the bacon fat in the pot.
Add the onion and celery to the pot and sauté for 5 minutes or until lightly browned.
Stir in the garlic and cook for about 30 seconds.
Add the broth, passata, beans, Italian seasoning, and sugar to the pot. Give it a good stir, increase the heat to high, and bring it to a boil.
Once boiling, add in the shellbows and about 3/4 of the bacon (reserve the rest for topping each bowl). Cook, uncovered (or with the lid slightly open) for 20 minutes or until the pasta is cooked. Stir it fairly often so the pasta doesn't stick, and adjust the heat as needed to maintain a rapid simmer. Add more chicken broth if the soup gets too thick.
Add in the spinach and let it wilt, then season the soup with salt & pepper as needed and serve immediately with the remaining bacon sprinkled on top, along with some freshly grated parmesan cheese.