Heat olive oil in a large pot over medium heat.
Add chopped onion and sauté until translucent.
Stir in minced garlic, carrots, and celery; cook for 5 minutes.
Add diced tomatoes and cook for another 5 minutes.
Pour in the broth and bring to a boil.
Add the cannellini beans and season with salt and pepper.
Reduce heat and simmer for 10 minutes to meld flavors.
Stir in the ditalini pasta and cook until al dente, about 8-10 minutes.
Adjust seasoning to taste.
Serve hot, garnished with fresh parsley.