01 - Melt the butter in a large pot or Dutch oven over medium heat. Add the chopped onion and diced carrots, and sauté for about 5 minutes until the vegetables are softened and the onion is 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 vegetables and stir well to combine. Cook for 1 minute, stirring constantly, to remove 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 mixture to a gentle simmer.
05 - Add the diced chicken breasts, dried thyme, salt, pepper, and nutmeg (if using). Maintain a simmer and cook for 8 to 10 minutes, or until the chicken pieces are cooked through and no longer pink inside.
06 - Stir in the orzo pasta and cook for 7 to 8 minutes until tender, stirring occasionally to prevent the pasta from sticking to the bottom of the pot.
07 - Reduce the heat to low. Pour in the heavy cream and add the grated Parmesan cheese. Stir gently until the cheese has fully melted and the soup reaches a smooth, velvety consistency.
08 - Fold in the chopped spinach and cook for 2 to 3 minutes, just until the leaves are wilted and bright green.
09 - Taste the soup and adjust the salt and pepper as needed. Ladle into bowls and garnish with fresh chopped parsley if desired. Serve hot.