It is better to add cooked rice to the casserole than uncooked rice. It will shorten the casserole baking time. 1. Rinse one cup of dry rice with water before cooking (optional). 2. Next, add 2 cups of water to the rinsed rice in a pot, and season it with salt and pepper to taste. 3. Bring it to a boil and simmer on medium-low heat until most of the water is absorbed. 4. Then, cover the pot and cook for 10 minutes on low heat or until the rice is soft and fluffy.