Baked Onions au Gratin
In two batches, sauté the onion in the butter in a large frying pan. Cook only until limp. Do not brown or discolor.
Deglaze the pan, or remove the onion from the pan and pour sherry, scrapping the pan with a wooden spoon to dissolve the brown, toasted onions.
Mix the onions, the sherry, nutmeg, salt, pepper and heavy cream together and place in a baking dish. Top with the Swiss and then Parmesan or Romano.
Bake at 350 until top is a bit brown and bubbling, 15 - 20 minutes.