First things first, make sure your chicken is cooked and diced. Set that aside.
Grab a large pot or a deep skillet – the bigger, the better for everything to fit comfortably. Heat the butter and olive oil over medium heat until the butter is melted and bubbly.
Add your finely diced celery, carrots, and onion to the pot. Cook them, stirring occasionally, until they start to soften, about 5-7 minutes. We're not looking for deep brown color, just tender-crisp veggies.
Now, sprinkle the flour over the cooked vegetables. Stir it well and cook for just 1-2 minutes, stirring constantly. This step cooks out the raw flour taste and creates a roux, which will thicken our sauce.
Slowly pour in the chicken broth while whisking constantly. Make sure to scrape the bottom of the pot to get any bits that might be stuck. Keep whisking until the mixture is smooth and starts to thicken slightly.
Stir in the heavy whipping cream, chicken bouillon powder, onion powder, garlic powder, paprika, and a good pinch of salt and pepper. Bring the mixture to a gentle simmer.
Add the orzo pasta to the simmering sauce. Stir it in well to make sure it's all submerged.
Bring the mixture back to a gentle simmer, then reduce the heat to low, cover the pot, and cook for about 10-12 minutes, or until the orzo is al dente (cooked through but still has a slight bite). Stir every couple of minutes to prevent the pasta from sticking to the bottom. This is important!
Once the orzo is cooked, stir in your diced cooked chicken. Cook for just a minute or two more, or until the chicken is heated through.
Taste the orzo and add more salt and pepper if needed. If the sauce seems too thick, you can stir in a splash more broth or cream until it reaches your desired consistency.
Serve hot! This is fantastic on its own or with a simple side salad or some crusty bread for dipping.