Combine rice, water and butter (optional) in a pot and bring to the boil. Cover with a tight-fitting lid, reduce heat to low and cook for 40 minutes. Remove from heat (with lid on!) and let stand for 10 minutes. Stir with a fork.
To prepare in a rice cooker, use the same proportion of water and rice. If the rice is crunchy at the end of cooking, it may be necessary to add 15 to 30 mL (1 to 2 tablespoons) of liquid and cook longer.