Heat olive oil in a large pot over medium heat. Sauté chopped onion for 3-4 minutes until translucent. Add diced carrots and celery, cooking for another 5 minutes.
Stir in drained white beans and pour in vegetable broth. Increase heat to bring to a gentle boil.
Reduce heat to low, add minced garlic, dried thyme, and dried rosemary. Season with salt and pepper. If using, add greens.
Cover and let the soup simmer for 20-25 minutes, stirring occasionally.
Taste and adjust seasoning. Optionally blend part of the soup for a creamier texture. Serve hot, garnished with olive oil or fresh herbs.