Heat the olive oil in a large pot over medium heat.

Add the onion, carrots, and celery. Cook for 6 to 8 minutes, stirring occasionally, until softened.

Stir in the garlic, rosemary, thyme, and red pepper flakes, and cook for 1 minute until fragrant.

Add the tomato paste and cook for 1 minute, stirring to coat the vegetables.

Pour in the vegetable broth and water, then add the cannellini beans, diced tomatoes, bay leaf, salt, and black pepper.

Bring the soup to a boil, then reduce the heat to low and simmer uncovered for 20 minutes.

Remove the bay leaf. Use a spoon or potato masher to mash some of the beans against the side of the pot for a thicker texture, if desired.

Stir in the kale and cook for 3 to 5 minutes, until wilted and tender.

Turn off the heat and stir in the lemon juice. Taste and adjust seasoning with more salt and pepper if needed.

Ladle into bowls and serve warm, topped with Parmesan cheese if desired.