01 - Melt butter in a large pot or deep skillet over medium heat. Add onions, carrots, and celery, sautéing for 4 to 5 minutes until the vegetables begin to soften.
02 - Stir in the minced garlic and cook for 1 minute until fragrant.
03 - Sprinkle flour over the vegetables, stirring to coat evenly. Cook for 1 minute to remove the raw flour taste.
04 - Slowly whisk in the chicken broth, then add the milk. Bring to a gentle simmer, stirring constantly to prevent lumps.
05 - Add orzo, thyme, parsley, salt, and pepper, stirring well. Reduce heat to medium-low and simmer uncovered for 10 to 12 minutes, stirring occasionally to prevent sticking, until the orzo is al dente and the sauce has thickened.
06 - Stir in the heavy cream, cooked chicken, and frozen peas. Simmer for 3 to 5 more minutes until the chicken is heated through and the peas are tender. Adjust seasoning as needed.
07 - Remove from heat and let sit for 2 to 3 minutes to allow the sauce to thicken further. Garnish with extra parsley and serve warm.