Yes, you can put uncooked rice in a casserole. Rice will cook on its own if there is enough liquid in it. So make sure you have enough sauce in the casserole so that the rice gets cooked properly and doesn’t get dry. I strongly suggest sticking to the measurements given below while making this casserole. It's super easy to make the result will be delicious when you follow the measurements correctly. If you are making it for the first time, just make sure you have twice the amount of liquid as your rice. For example, if you are using 1 cup of rice, just take 2 cups of liquid to make the Rice casserole. If you want it more creamy, then you can add more sauce in it.