Bring A Large Pot Of Lightly Salted Water To A Boil. Add Pasta And Cook For 8 To 10 Minutes Or Until Al Dente; Drain. Meanwhile, Cook Chicken In Microwave Until Almost Cooked Through (Juices Run Almost Clear). Preheat Oven To 325 Degrees F (165 Degrees C). Saute Onion And Mushrooms In A Medium Saucepan Until Soft. Add Chicken, Bouillon And Water To Cover. Simmer Over Medium Low Heat, Seasoning With Salt And Pepper To Taste. Add Cooked Spaghetti And Cream And Mix All Together; Finally, Stir In The Cheese. Bake In Preheated Oven For 20 To 30 Minutes, Or Until Cooked Through. Halfway Through Cooking, Check Dish And Add More Parmesan Cheese If Desired, To Taste.