Bring a large pot of lightly salted water to a boil, add pasta and cook until al dente. Drain well, do not rinse.
Meanwhile heat butter in skillet over medium heat. Add onions and cook until tender, about 5 minutes. Add the flour to the onions and cook 1 minute.
Gradually stir in beef broth and simmer until slightly thickened. Whisk in the onion dip or sour cream. Combine the onion sauce and noodles in a 2 quart baking dish.
Mix topping ingredients and sprinkle overtop. Bake 15-20 minutes or until heated through.
Notes
If using sour cream, add additional seasonings including garlic powder, salt, pepper and paprika.
Refrigerate leftovers for up to 4 days and reheat on the stove or in the microwave.