Preheat and prep the pan. Heat your oven to 375°F (190°C).
Lightly coat a 9x13-inch baking dish with nonstick spray.
Combine the base. In the baking dish, whisk together the cream of chicken soup, chicken broth, sour cream, garlic powder, onion powder, thyme, paprika, a pinch of salt, and pepper until smooth.
Add the rice and veggies. Stir in the uncooked long-grain white rice and the frozen peas and carrots. Spread the mixture evenly in the dish.
Add the chicken. Nestle the chicken pieces throughout the dish and gently press them so they’re mostly submerged. Sprinkle half the cheese over the top.
Cover tightly. Cover the dish tightly with foil. A tight seal prevents moisture loss and ensures the rice cooks through.
Bake. Bake for 40 minutes covered.
Remove the foil, stir gently, and check the rice. If most of the liquid is absorbed but the rice needs a bit more time, recover and bake another 10–15 minutes.
Add topping and finish. If using the cracker or panko topping, mix it with melted butter and the remaining cheese. Sprinkle over the top.
Bake uncovered for 5–10 minutes more, until the cheese is melted and the topping is golden.
Check doneness. The chicken should be at least 165°F in the center, and the rice should be tender with no crunch. If needed, add a splash of broth and bake a bit longer.
Rest and serve. Let the casserole rest for 5–10 minutes so it sets and thickens. Taste and adjust salt and pepper before serving.