Preheat the oven to 350°F. In a large mixing bowl, thoroughly combine all ingredients, reserving 1 ½ cups of the shredded cheese for the topping. Transfer the mixture into a greased 9×13-inch (5-quart) glass baking dish, smoothing the surface evenly. Sprinkle the reserved cheese uniformly over the top. Cover the dish with aluminum foil and bake for 45 minutes. Remove the foil, return the casserole to the oven, and continue baking uncovered for an additional 45 minutes, or until the top is golden and the edges are bubbling.