In a large pot, heat the olive oil over medium heat. Add the diced onion and sauté for about 5 minutes until translucent.
Stir in the minced garlic, diced carrot, and diced celery. Cook for another 5 minutes until the vegetables are softened.
Add the crushed tomatoes, cannellini beans, vegetable broth, dried basil, and dried oregano. Season with salt and pepper. Bring the mixture to a boil, then reduce the heat and let it simmer for 20 minutes.
Stir in the fresh spinach and lemon juice. Cook for an additional 5 minutes until the spinach is wilted.
Taste and adjust seasoning if necessary. Serve hot, topped with grated Parmesan cheese if desired.