Boil chicken until done. Remove chicken from water and let cool.
While boiling water for noodles, slice mushrooms and dice onions. Fry together in pan with a teaspoon of butter, salt to taste, until done to your liking. Remove from hear and set aside.
Take the chicken now cold, and cut into small pieces. Put in with mushrooms and onions.
Boil shells in water until done.
In a big bowl put hot noodles. Add the cheese, mushroom, onion, chicken, Ranch dressing, and mix all together. Serve.