Preheat your oven to 350°F. While it’s heating, add a little oil to a pan over medium heat. Sauté the chopped celery, onion, and garlic for about 5 minutes until they’re soft and fragrant. This builds the foundation of flavor in your casserole, so don’t skip this step.
In a large mixing bowl, combine the cooked chicken, cream of chicken soup, sour cream, and chicken stock. Add the sautéed vegetables into the bowl. Stir everything well until you get a creamy, consistent mixture. Slowly fold in your cooked wild rice, making sure everything is coated nicely.
Lightly grease your baking dish to avoid sticking. Pour the rice and chicken mixture into the dish and spread it evenly. Sprinkle the grated parmesan cheese across the top for that irresistible golden crust. Don’t skimp—it makes a big difference!
Place the dish into your preheated oven and bake for 35–40 minutes. The top should be lightly golden and bubbling around the edges. Once it’s done, let it rest for about 5 minutes before serving. This helps it set and makes it easier to portion.