Preheat oven to 375 F.Lightly grease a 9x13- inch baking dish.Add frozen onion rings and 1 cup parmesan cheese;mix well.
Bring a large pot of lightly salted water to a boil.Add macaroni and cook for 8 to10 minutes or until al dente;drain.Add french onion soup mix on macaroni and toss together.
Meanwhile,melt the margarine in a medium skillet over medium heat.Stir in the onions and saute for 3 minutes until it begins to soften.Add brown sugar and continue cooking until the onions are caramelized for 5 minutes.
To make French Onion Cheese Sauce:in a large saucepan,combine milk,french onion dip,cream cheese,half and half,sharp cheddar,monterey jack and swiss cheese.Stir in over medium-low heat,simmer for 10 minutes until thickened.
Add onion mixture and macaroni,continue stirring until blended.
Pour into the prepared baking dish.Sprinkle with remaining parmesan cheese and bread crumbs over the macaroni mixture.
Bake in preheated oven until bubbly and brown,about 30 minutes.Remove from the oven and allow to stand 5 to 10 minutes before serving.