Heat the butter in a casserole, add the sliced onions, sprinkle with salt and pepper and place the brace of pheasants on the top, prepared with the bacon as for roasting.
Pour the cream sauce over the birds, cover tightly with foil and cook slowly in the oven at 220ºC 425ºF / gas mark 7 for one to one-and-half hours. Take out the pheasants and cut into neat joints. Lay them on a dish and keep warm.
Now pass the onions and sauce through a fine strainer; re-boil, taste for seasoning, pour over the pheasant pieces and serve. Small button onions, fried in butter, may be served around the dish if desired.