Preheat oven to 400°F. Cook pasta as directed on package. Drain well.
Meanwhile, break up Italian sausage in large skillet. Cook on medium heat 5 minutes or until cooked through. Drain fat.
Mix sausage, spaghetti sauce, onions, basil, oregano and pepper in 9-inch deep dish pie plate or 2 1/2-quart casserole. Add pasta; mix well. Sprinkle with mozzarella slices.
Bake 15 to 20 minutes or until cheese is melted and mixture is heated through.