01 - Heat olive oil in a large pot or deep skillet over medium-high heat. Season diced chicken with salt and pepper, then cook until golden and cooked through, approximately 5 to 6 minutes. Transfer chicken to a plate and set aside.
02 - Add butter to the same pot. Once melted, add onions, carrots, and celery. Sauté the vegetables until softened, about 5 minutes.
03 - Sprinkle flour evenly over the vegetables, stirring constantly to coat. Cook for 1 minute to form a roux and remove the raw flour taste.
04 - Gradually pour in chicken broth while whisking or stirring vigorously to prevent lumps. Bring the mixture to a gentle simmer.
05 - Stir in orzo pasta, garlic powder, thyme, and parsley. Reduce heat to medium-low and cook uncovered, stirring occasionally to prevent sticking, until the pasta is al dente, about 10 minutes.
06 - Add the cooked chicken and frozen peas to the pot. Simmer for an additional 3 minutes to heat the chicken through.
07 - Pour in heavy cream and add Parmesan cheese. Stir continuously until the sauce is creamy and the cheese has melted. Adjust final seasoning with salt and pepper to taste.
08 - Serve the dish hot while the sauce is bubbly. Garnish with additional parsley or Parmesan if desired.