1Preheat the oven to 350 degrees F (175 degrees C).
2In a large bowl, combine the bread cubes and onion. Pour in the whole kernel corn, cream style corn and milk. Season with sugar, salt and pepper and stir to blend everything evenly. Transfer to a greased 2 quart casserole dish. In a separate bowl, toss together the rice cereal and melted butter. Sprinkle over the top of the casserole.
3Bake uncovered for 45 minutes in the preheated oven, or until the top is toasted and the corn is heated through.