In a large Dutch oven, heat the oil over medium heat. Add the carrot, celery, onion, basil, salt, and pepper. Let cook until the vegetables soften and are beginning to brown, about 8 minutes (don’t rush this step; it builds important flavor).

Add the garlic and cook, stirring constantly, until fragrant, about 30 seconds.

Sprinkle the flour over the top and stir until it disappears. Pour in 6 cups of the chicken broth and stir to combine. The flour should be completely dissolved.

Carefully lower the chicken into the broth. Bring the soup to a boil, then reduce the heat, partially cover the pot, and let gently simmer for 10 to 15 minutes, until the chicken is cooked through and reaches 165 degrees F on an instant-read thermometer. Check the soup periodically to make sure you are maintaining a gentle simmer vs. a rapid boil.

Remove the chicken to a cutting board and cover. Let rest for at least 5 minutes.

Return the soup to a simmer, then stir in the orzo. Continue to simmer for 7 additional minutes, stirring periodically to keep the orzo from sticking, until the orzo is very al dente (it should be nearing done but still be too firm to eat).

Dice or shred the chicken, then add it to the pot.

Stir in the spinach, lemon juice, and dill. If you desire a thinner soup, add the remaining 1 to 2 cups of chicken broth, until the soup is to your liking. Continue to simmer and stir periodically for 3 to 5 additional minutes, until the spinach wilts and the orzo is al dente. Taste and add additional salt and pepper as desired. Enjoy warm.