Heat olive oil in a large Dutch oven or soup pot over medium-high heat. Add ground turkey and cook, breaking it up with a spoon, until browned and cooked through, about 5-7 minutes. Drain any excess fat. Remove turkey from the pot and set aside.

Add chopped onion, diced carrots, and diced celery to the same pot. Cook over medium heat, stirring occasionally, until vegetables are softened, about 6-8 minutes. Add minced garlic and tomato paste, cook for another 1-2 minutes, stirring constantly, until fragrant.

Stir in diced tomatoes (undrained), chicken broth, water, dried oregano, dried basil, salt, and black pepper. Bring the mixture to a boil, then reduce heat to low, cover, and simmer for 10 minutes to allow flavors to meld.

Return the cooked ground turkey to the pot. Add the ditalini pasta. Increase heat to medium and cook, stirring occasionally, until pasta is al dente, about 7-9 minutes, or according to package directions.

If using, stir in fresh spinach and cook until just wilted, about 1-2 minutes. Taste and adjust seasonings as needed.

Ladle hot soup into bowls. Garnish with freshly grated Parmesan cheese and chopped fresh parsley before serving.