In a large pot, heat olive oil over medium heat. Add diced onion, carrots, and celery, and sauté until softened, about 5 minutes.

Add minced garlic and cook for an additional minute until fragrant.

Pour in the vegetable broth and add the cannellini beans. Bring to a simmer and cook for 20 minutes.

In a blender, combine basil leaves, parmesan cheese, pine nuts, minced garlic, and salt.

With the blender running, slowly drizzle in the olive oil until the mixture is smooth and creamy.

Once the soup base is ready, use an immersion blender to puree the soup until smooth, or transfer to a regular blender in batches.

Stir in the prepared pesto and adjust seasoning with salt and pepper to taste.

Serve hot, garnished with additional pesto if desired.