Sauté the veggies: In a spacious saucepan, warm some olive oil over medium heat. Toss in the chopped onion, carrots, and celery. Cook for 5-6 minutes, stirring occasionally, until the vegetables become tender. Then, add the minced garlic and sauté for an additional minute until aromatic.

Add the broth and herbs: Pour in the chicken broth and stir in the dried thyme, dried oregano, and black pepper. Bring the mixture to a boil.

Cook the rice: Once the soup is boiling, add the uncooked rice. Lower the heat to a simmer and cook for 15-20 minutes, or until the rice is tender, stirring occasionally to prevent it from sticking to the bottom of the pot.

Add the chicken and greens: Stir in the cooked chicken and, if using, the fresh spinach or kale. Allow the soup to simmer for another 5 minutes to heat the chicken through and wilt the greens.

Season to taste: Taste the soup and add salt as needed.

Serve: Ladle the soup into bowls and garnish with freshly chopped parsley for an added burst of flavor. Serve with crusty bread or on its own for a complete meal.