in large saucepan, melt butter, put in flour to create a paste, add salt, pepper and slowly add milk, mixing while it heats up. When milk starts to thicken, start adding cheese until melted. (you can add as much cheese as you'd like... recipe is just a suggestion)
place pasta in large greased,casserole pan. Add soup to cheese mix and then add to the pasta. Place fried onions on top and bake at 350 until golden brown about 30 mins.