Heat olive oil in a large pot over medium heat. Add chicken thighs and sear until browned, about 5 minutes per side. Remove and set aside.
In the same pot, add onion, carrots, and celery. Sauté for 6 minutes until softened. Stir in minced garlic and cook for 1 minute.
Pour in the chicken broth, crushed tomatoes, diced potatoes, and dried oregano. Bring the mixture to a boil.
Shred the rested chicken and return it to the pot. Reduce heat, cover, and simmer for 20 minutes.
Stir in the ditalini pasta and cook for an additional 10 minutes until the pasta is tender.
Remove from heat. Stir in fresh basil and serve hot, garnished with grated Parmesan cheese.