Heat butter and olive oil in a large soup pot over medium-high heat. Add celery, carrots, and onion, and sauté for 5-7 minutes.

Stir in garlic and cook for 30 seconds, then add flour and cook for 1 minute.

Pour in chicken broth, stirring until flour dissolves. Add Italian seasoning and chicken. Bring to a boil.

Reduce heat and simmer for 15 minutes with the lid slightly open.

Stir in the orzo and cook for 10 minutes, stirring often to prevent sticking.

Remove chicken from the pot, cut into pieces, and return to the soup.

Stir in lemon juice and parsley. Season with salt and pepper to taste.

Serve hot and enjoy!