Half roast a grouse or partridge in butter in a saute pan, with an onion cut in quarters, then take the bird and put it in a little casserole. In the saute pan, where the bird has been cooking, put a liqueur glass of vinegar and reduce to half, add 1/2 pint of cream, and boil with salt and pepper and a little cayenne. Strain it over the bird in the casserole, cook slowly for ten minutes in the cream, and serve.