Preheat oven to 350°. Prepare rice and sauce with water and butter according to package directions. Meanwhile, in 10-inch skillet, brown ground beef over medium-high heat; drain. Stir into rice and sauce. Fill each pepper half with rice mixture.
In 13 x 9-inch baking dish, arrange stuffed peppers. Bake covered 20 minutes. Remove cover and continue baking 10 minutes, or until peppers are tender. Sprinkle, if desired, with shredded cheddar cheese. Serves 4 (from Lipton Kitchen Taste Tested Recipes)