01 - Melt the butter in a large pot or Dutch oven over medium heat. Add the chopped onion and diced carrots, sautéing for 5 minutes until the vegetables are softened and the onion turns translucent.
02 - Stir in the minced garlic and cook for 1 minute until fragrant, being careful not to let it brown.
03 - Sprinkle the flour over the vegetable mixture, stirring constantly for 1 minute to cook off the raw flour taste and form a light roux.
04 - Slowly pour in the chicken broth while stirring continuously to prevent any lumps from forming. Bring the liquid to a gentle simmer.
05 - Add the diced chicken, dried thyme, salt, pepper, and nutmeg if using. Maintain a steady simmer for 8 to 10 minutes until the chicken is cooked through and no longer pink in the center.
06 - Stir in the orzo pasta and cook for 7 to 8 minutes, stirring occasionally to keep the pasta from sticking to the bottom of the pot, until the orzo is tender.
07 - Reduce the heat to low. Pour in the heavy cream and add the Parmesan cheese, stirring gently until the cheese has fully melted and the soup reaches a smooth, creamy consistency.
08 - Fold in the chopped spinach and cook for 2 to 3 minutes until just wilted and bright green.
09 - Taste the soup and adjust the salt and pepper as needed. Ladle into bowls and garnish with fresh parsley if desired. Serve hot.