Creamy chicken and rice baked in one dish is an effortless family dinner that's warm and comforting. Packed with protein and perfect for busy weeknights, this chicken casserole pleases every palate.
Preheat your oven to 375°F. Grease a 9x13-inch baking dish with butter.
In a large skillet over medium heat, melt 2 tbsp butter. Add onions, celery, and carrots; sauté for 5 minutes until softened.
Stir in mushrooms and cook for another 3 minutes. Sprinkle flour over the vegetables and stir for 1 minute to cook off the raw taste.
Slowly pour in chicken broth and milk while stirring, making sure no lumps remain. Add garlic powder, dried thyme, salt, and black pepper. Simmer for 3 minutes to slightly thicken.
Turn off heat. Stir in uncooked rice and half of the parsley. Transfer mixture into the prepared baking dish.
Nestle chicken thighs evenly over the rice mixture. Lightly season chicken tops with extra salt and pepper if desired.
Cover tightly with foil and bake for 40 minutes. Remove foil, baste chicken and rice with pan juices, and bake uncovered for 20-25 minutes more until rice is tender and chicken is cooked through.
Let the casserole rest for 5-10 minutes. Sprinkle remaining parsley over the top before serving.