Cook the onion in butter for 5 minutes, stirring constantly and do not let it brown.
Add the sliced mushrooms and seasonings and let simmer for 15 minutes.
Turn the mixture into an oblong baking dish and arrange chicken and ham on the top.
Add enough hot cream to cover the meat.
Let simmer in a hot 400 degree oven for 10 minutes.
Cover with Parmesan cheese; let remain in oven until cheese is browned.