In a large stock pot or dutch oven, heat the olive oil over medium heat.
Add onion, carrot and celery. Cook about 5 minutes, stirring frequently, until veggies are softened. Add garlic and saute 1 minute.
Add rosemary and chili flakes. Stir and cook about 1 min.
Add vegetable broth and potatoes. Bring to a slight boil, then turn down heat. Simmer for 8 minutes.
Add the beans, and continue to simmer for about 5 more minutes.
Ladle about half of the soup into a blender. Carefully blend just until creamy. Return mixture to the pot.
Add spinach to the soup, turn down heat to low and cook until spinach just starts to softens.
Add lemon juice and salt & pepper to taste. Add extra water/broth as needed.