Plunge the spaghetti into plenty of boiling salted water.
Allow to boil gently.
Stir occasionally with a wooden spoon.
Cook for approx. 12-15 min.
Drain well in a colander.
Return to a clean pan containing the butter.
Add tomato sauce.
Correct the seasoning.
Add the julienne of ham and mushroom ; mix in carefully.
Serve in an earthenware dish on a silver flat with grated cheese separately.