Step 1: Heat the olive oil in a large pot over medium heat. Add the chopped onion and garlic, and sauté for 2-3 minutes until they become soft and fragrant.

Step 2: Add the diced carrots and celery to the pot. Cook for another 3-4 minutes, stirring occasionally.

Step 3: Pour in the chicken broth and bring the mixture to a simmer.

Step 4: Add the chicken breasts, turmeric powder, lemon juice, lemon zest, salt, and black pepper. Cover the pot and let it simmer for 15-20 minutes, or until the chicken is cooked through.

Step 5: Remove the chicken breasts from the pot and shred them using two forks. Return the shredded chicken to the pot.

Step 6: Stir in the baby spinach and allow it to wilt, which should take about 1-2 minutes.

Step 7: Taste the soup and adjust the seasoning if necessary.

Step 8: Ladle the soup into bowls and garnish with fresh parsley before serving.