Preheat your oven to 180°C and prepare a large bowl where you combine rice, broth, milk, soup, and sour cream until smooth and evenly mixed.
Add chicken, vegetables, onion, garlic, and spices, then stir thoroughly so every ingredient is well distributed throughout the mixture.
Transfer everything into a greased casserole dish and spread it evenly to ensure consistent cooking across the dish.
Cover tightly with foil and bake for 30 minutes so the rice absorbs liquid and softens properly without drying out.
Remove foil, add cheese and optional breadcrumb topping, then bake uncovered until golden and bubbling.
Let the casserole rest briefly before serving so the texture sets and flavors come together fully.