01 - Heat olive oil in a large pot or deep skillet over medium-high heat. Season diced chicken with salt and pepper, then add to the pot. Cook until golden brown and cooked through, approximately 5-6 minutes. Remove chicken from the pot and set aside on a plate.
02 - Reduce heat to medium. Add the butter to the same pot and allow it to melt. Add the diced onion, carrots, and celery. Sauté the mixture until the vegetables begin to soften, about 5 minutes.
03 - Sprinkle the flour evenly over the cooked vegetables. Stir constantly to coat the vegetables and cook the flour for about 1 minute to create a roux base.
04 - Gradually pour in the chicken broth while whisking or stirring vigorously to prevent lumps from forming. Bring the mixture to a gentle simmer.
05 - Stir in the dry orzo, garlic powder, dried thyme, and dried parsley. Reduce heat to medium-low and cook uncovered. Stir occasionally to prevent sticking, and continue cooking until the orzo is al dente, roughly 10 minutes.
06 - Add the cooked chicken and frozen peas to the pot. Stir well and let the mixture simmer for an additional 3 minutes to heat the chicken and peas through.
07 - Pour in the heavy cream and add the grated Parmesan cheese. Stir until the cheese is melted and the sauce is creamy and smooth. Taste the dish and adjust the seasoning with salt and pepper as needed.
08 - Ladle the hot orzo into bowls. Garnish with additional parsley or Parmesan cheese if desired, and serve immediately.