
Sauté the vegetables
Heat the olive oil in a large saucepan over medium heat. Add the chopped onion, celery, and carrots. Cook for 4–5 minutes until the vegetables start to soften.
Make the roux
Sprinkle the flour over the vegetables. Stir using a whisk to coat everything evenly.
Add milk
Gradually pour in the milk while whisking continuously until smooth and well incorporated.
Pour in stock and season
Add the hot chicken stock and dried thyme. Stir well.
Cook the rice
Stir in the rice, bring the soup to a boil, then reduce to a simmer. Cook uncovered for about 25 minutes, stirring occasionally, until the rice is tender.
Finish the soup
Add the shredded chicken, lemon juice, cream, Parmesan cheese, salt, and pepper. Stir to combine and heat through for a few more minutes.
Serve
Sprinkle with chopped parsley before serving.