Preheat oven to 325. Melt half the butter in a large skillet over medium heat and sauté onions until transparent. Remove from heat. While onions sauté cook rice in boiling, salted water for 5 minutes; drain well. Mix rice into the onions, along with cheese and half n’ half. Season with salt and pepper and add remaining butter. Turn into a 2 ½ quart baking dish and bake 1 hour. Serve hot.