Heat olive oil in a large saucepan or dutch oven over medium heat.
Sauté chopped onion until it starts to get translucent, about 3-5 minutes.
Add garlic and cook for about another minute. Be careful not to let the garlic burn; add more olive oil and adjust heat as necessary.
Add the beans, celery, bay leaf, rosemary, thyme, parsley, and salt and pepper to taste.
Add the vegetable broth, stir and bring to a boil.
Cover the pot and simmer for 30-45 minutes, until beans are tender.
Remove from heat and allow the beans to cool for about 20 minutes.
Pour the bean mixture into a food processor (or use a hand-held immersion blender) to purée the soup.
Warm the soup on low in the saucepan. Drizzle in lemon juice and additional olive oil before serving. Optionally add chives, shaved parmesan, and additional fresh ground pepper.