Preheat your oven to 375°F and lightly grease a 9x13-inch baking dish.
In a medium bowl, combine the chicken with the olive oil, balsamic vinegar, salt, black pepper, garlic powder, and Italian seasoning. Toss until the chicken is evenly coated, then let it marinate in the fridge for at least 15 minutes while you prepare the remaining ingredients.
In the prepared baking dish, whisk together the chicken stock, heavy cream, balsamic vinegar, and tomato paste until smooth.
Add the dry orzo, minced garlic, parmesan, salt, black pepper, onion powder, and Italian seasoning. Stir until everything is well combined.
Fold the marinated chicken into the orzo mixture, spreading it into an even layer. Scatter the cherry tomatoes and mozzarella pearls evenly over the top.
Cover tightly with foil and bake for 35 minutes. Remove the foil, give the orzo a gentle stir, then return the dish to the oven uncovered for another 20 minutes, or until the chicken is cooked through and the orzo is tender.
Let the bake rest for 10 minutes before serving so the sauce has time to thicken.
Finish with freshly grated parmesan, chopped basil, cracked black pepper, and a generous drizzle of balsamic glaze.