In a large pot, heat the olive oil over medium heat. Add the diced onion and sauté for about 3-4 minutes until translucent.
Stir in the minced garlic, diced carrot, and diced celery. Cook for an additional 5 minutes, stirring occasionally.
Add the diced red bell pepper and zucchini to the pot, cooking for another 3-4 minutes until they begin to soften.
Pour in the diced tomatoes with their juice and vegetable broth. Stir in the dried basil, dried oregano, salt, and pepper. Bring the mixture to a boil.
Reduce the heat and let it simmer for 15-20 minutes, allowing the flavors to meld together.
Add the cannellini beans and fresh spinach to the pot. Cook for another 5 minutes until the spinach is wilted.
Stir in the lemon juice and adjust seasoning if necessary. Serve hot, topped with grated Parmesan cheese if desired.