01 - Melt butter in a large pot or deep skillet over medium heat. Add the onions, carrots, and celery. Cook for 4 to 5 minutes, stirring occasionally, until the vegetables begin to soften.
02 - Stir in the minced garlic and cook for 1 minute until fragrant, being careful not to let it brown.
03 - Sprinkle the flour evenly over the vegetables and stir to coat thoroughly. Cook for 1 minute to remove the raw flour taste.
04 - Slowly whisk in the chicken broth, then pour in the milk. Bring to a gentle simmer, stirring constantly to prevent lumps from forming.
05 - Add the orzo pasta, dried thyme, dried parsley, salt, and black pepper. Stir well to combine. Reduce heat to medium-low and simmer uncovered for 10 to 12 minutes, stirring occasionally to prevent the pasta from sticking, until the orzo is al dente and the sauce has thickened.
06 - Stir in the heavy cream, cooked chicken, and frozen peas. Continue simmering for 3 to 5 minutes until the chicken is heated through and the peas are tender. Taste and adjust seasoning as needed.
07 - Remove from heat and let the dish rest for 2 to 3 minutes so the sauce thickens further. Garnish with additional parsley and serve warm.