WASHINGTON in the years after World War II was nobody's gourmet capital. To a naive -- if indiscrimnately hungry -- New Yorker, though, it was a very differnet place to cook andeat.

So southern.

In those days, when young couples invited each other over to dinner in these parts, the critical item on the menu -- the one to make or break a culinary reputation -- was likely to be the hot biscuits. Some women used Bisquick and some used biscuit dough that came ready-mixed in a cardboard cylinder. But the women who were building reputations as cooks made their own biscuits from scratch, and such distinctions stood or fell on the lightness of the product.

To be sure, some made cornbread or muffins or popovers rather than biscuits. Some even got into yeast and turned out puffy soft rolls for admiring guests. Hot bread remained a primary measure of culinary expertise. It went so well with the ham and fried chicken.

New Yorkers, to whom ham tended to signify the thinly sliced pink substance bought in the delicatessen for sandwiches, didn't know much about either Virginia's Smithfield or Maryland's kale-and-parsley-stuffed ham. Many subscribed to the notion that -- except for ham-sandwich ham, bacon and an occasional sausage to go with the breakfast pancakes -- pork was an indigestible and dangerous meat.

A New Yorker, for that matter, didn't know much about fried chicken, back then, before the fast-food era had put it on everybody's plate from Maine to New Mexico. There was even a tendency to dismiss it as one more evidence of the South's taste for greasy fried foods northerners considered bad for the health.

Washington's seafood was more congenial. Anybody who loved Long Island oysters loved Chesapeake Bay oysters even more. And while more northern waters yielded greater bounty in the way of lobsters and steamer clams, the crabs of the Chesapeake made up for everything.

The crab feast was a perennial in D.C. entertaining. Preferably held on a screened porch or back-yard picnic table, it featured newspaper tablecloths, plenty of nutcrackers and plenty of crabs from Maine Avenue. The crabs, cooked in beer or water with garlic, a bay leaf and Old Bay seasoning, were presented on big platters and attacked without benefit of knives and forks, and there was more beer to drink. Happily, it's a custom that hangs on.

There were still country markets in several parts of Washington then. Cheerful equivalents of the Eastern Market offered wonderful fresh produce at 21st and K NW and at 5th and -- was it Pennsylvania? The one at 21st and K had a lovely little Greek bakery next door, where the proprietor would offer small cups of sweet, mud-thick coffee with a purchase of baklava.

Back from an after-work foray into one of these markets, the young person expecting company for dinner was likely to think casserole. Changing mores had delivered us from the tyranny of courses. Knowing we did not have to duplicate the soup-to-nuts productions that had been expected of our mothers, we experimented with one-dish meals.

Chicken Divan, accompanied by nothing more than a salad, biscuits and a dessert, made us feel daringly modern. If the dinner party had been planned long enough in advance to work a black bottom pie into the schedule, so much the better. But ice cream and chocolate chip cookies would have to do if time was short.

Here are a couple of the casseroles that still evoke old Washington -- and still seem worth eating.

CHICKEN AND OYSTER CASSEROLE (4 servings) 1 frying chicken, cut up 1 cup water 1/2 cup vinegar 1 clove garlic 1 pinch dried thyme 1 bay leaf 1 teaspoon salt 1 pint oysters 2 tablespoons butter 1 tablespoon flour 2 tablespoons sherry 1 tablespoon parsley, minced 3 tablespoons bread or cracker crumbs

Simmer chicken in water and vinegar with garlic, thyme, bay leaf and salt for 30 minutes, or until tender. Cool and strip meat from bones, reserving liquid. Discard bones and skin and cut chicken meat into bite-sized pieces. Drain oysters, adding oyster liquor to liquid in which chicken was cooked. In a frying pan, melt 1 tablespoon butter and stir in flour. Stir in chicken and oyster liquid and simmer until slightly thickened. Add sherry and parsley and combine with chicken and oysters in 2-quart baking dish. Top with crumbs and remaining tablespoon of butter, cut in small bits. Bake 15 minutes at 350 degrees. Serve on hot biscuits.

CHICKEN DIVAN (4 servings) 1 frying chicken, cut up 1 clove garlic 1 pinch thyme Salt and pepper to taste 1 bay leaf 1 cup water 1/2 cup white wine 1 egg yolk 2 tablespoons cream 2 tablespoons pimiento 1 bunch broccoli, left whole lightly cooked and drained 2 tablespoons parmesan cheese

Simmer chicken with garlic, thyme, salt and pepper and bay leaf in water and white wine 30 minutes. Cool and separate meat from bones, reserving liquid. Discard skin and bones and cut meat into bite-sized pieces. Beat egg yolk with cream, add pimiento and stir into cooking liquid over low heat until slightly thickened. Arrange chicken in a 2-quart baking dish. Arrange broccoli on top. Distribute sauce on broccoli and top with parmesan cheese. Place under broiler until it begins to brown.

CRAB CASSEROLE (4 servings) 1 pound Chesapeake Bay crab meat 2 tablespoons butter 1 green pepper, chopped 1 bunch scallions, chopped 1 tablespoon flour 1 cup milk 3 tablespoons parmesan cheese

Carefully pick over crab meat to remove any shells pieces, then set aside. Melt butter and saute' pepper and scallions in it until softened. Sprinkle with flour and slowly stir in milk. Stir over low flame until it thickens slightly. Stir in crab and place in a 1-quart baking dish. Sprinkle with parmesan cheese and brown quickly under broiler. Serves 4.