THE WHITE House has its first woman chef, although she is an assistant -- and a part-time assistant at that. Ann Amernick, who once made the Big Cheese restaurant famous for its desserts, is a native Baltimorean, self-taught pastry chef, wife and mother of two children.

She went to the White House in February to help the new pastry chef, Roland Mesnier, who has been swamped with work since his arrival. The Carters have been entertaining more than any President since Lyndon Johnson. And the pace of entertaining has picked up significantly since Carter has been campaigning from the White House. There are often three parties a day, requiring dozens and dozens of sweets.

For Amernick, her five-day a week job in the White House kitchen is an opportunity to work with a top-notch pastry chef. White House Executive Chef Henry Haller says Mesnier is very good. Recently Amernick and another pastry chef, Patrick Musel, who works for Pasta Inc., won three prizes, including the grand prize for their pastry buffet at the annual culinary salon competition which is held each year in conjunction with the East-South regional Restaurant Exposition.

Love shrimp, but not at $20 a pound? If you love it enough to shell and devein them, you ought to try rock shrimp at $3 a pound. The flavor is excellent, a little like lobster, actually, once you get past the rather strong shell.

Until recently rock shrimp have been a treat only Southeasterners have enjoyed. That's because someone needed to invent a machine which could split and shell them in order to make the fishing worthwhile. Ironically, the ones available in Washington are not shelled, but I have discovered my own, relatively easy techmique for shelling them.

Rock shrimp, available at Safeway and A&P in 2 pound packages for $5.99, cook much more quickly than regualr shrimp. Put in boiling water frozen, they are ready in 45 seconds! Then they should be rinsed and as soon as they are cool enough to handle they can be shelled. Cut off the tail; then split the shell on the underside of the shrimp with a small sharp knife. The shell will pull off quite easily. The split in the shrimp will also reveal the sand vein, which should be removed.

These directions are contrary to those on the package which recommend shelling and then cooking. That's the hard way.

But beware. Some stores apparently have been selling rock shrimp as regular shrimp and charging regular shrimp prices. As soon as you see a rock shrimp in its shell you will know it is not the same. CAPTION: Picture 1, Linda Lovelace, by Tim Kelly; Picture 2, Samuel Twining, by Margaret Thomas

Fans of Mike McGrady's series "The Husband's Cookbook," may think Mike is still in the kitchen slaving away over a hot stove.

McGrady has been slaving away over something hot, but it isn't a stove. He's gone back to his original role in life -- writer -- and has gotten his name on the cover of a bestseller, "Linda Lovelace Ordeal."

Or, as the promotional blurb says: Linda Lovelace, "the actress who made porno chic (has been) trying to put distance between herself and the nightmare of her past. Ordeal is her story. Working with McGrady, she unburdens herself completely in these pages."

McGrady also put "The Husband's Cookbook" between hardcovers, but it probably isn't selling the way "Ordeal" is!

You'll have to get there early if you want one of the Cathedral Flower Mart's famous lobster rolls Friday. For the best selection of everything you ought to get there early -- whether its herbs for your own garden, homemade saffron and rye breads, split pea soup, a Dutch pancake luncheon to eat on the grounds, gifts for Mother's Day. This year's theme is Spring in Holland.

The ribbon-cutting ceremony, which opens the Flower Mart officially at 11 a.m., takes place on the south transept steps of the Washington Cathedral, Massachusetts and Wisconsin Avenues. The Mart closes at 5 p.m.

For all you chocoholics who get your kicks from chocolate fragrance, the publishers of Chocolate News have impregnated their newsletter with your favorite aroma.

If smelling isn't enough, this new newsletter will help you live vicariously through its chocolate taste tests, its recipes, its lists of America's favorite candy bar (Reese's Peanut Butter Cup in the Northeast but Snickers everywhere else).

If living vicariously isn't enough its first issue announced a chocolate lovers tour of Switzerland.

You want to know how to get chocolate stains out of clothes? It tells you that, too.

Chocolate News is out to sell chocolate, but it doesn't have to work very hard for the already committed.

Published bi-monthly, a year's subscription os $9.95 from Zel Publishing, F.D.R. Station, Box 5090, New York, N.Y. 10022.

Do you think you know where to find one of the 37 best ice cream creations in America? If so, American Reflections, which has already published the 37 best chocolate chip cookies in America, is looking for you.

Here's what they want: the best recipes for all kinds of ice cream dishes-- cakes, pies, tortes, puddings, sundaes, popsicles, drinks, parfaits, molds, mousses, candies, bombes, eclairs and what have you.

As one of the 37 contest winners you won't get much: recognition in the book containing the recipes, a free copy of the book and a dessert serving set, whatever that means.

Send your favorite recipe to: Ice Cream Creations, American Reflections, P.O. Box 3008, Princeton, N.J. 08540. Deadline is Sept. 30.

Samuel H. G. Twining, lord of the tea realm, ninth generation master of the flow-through tea bag, priviledged supplier to the Royal Family, had this to say about his infusive brew: "Tea is like wine. There are different teas for different foods and different moods."

Twining was in a very good mood as he sat drinking Lapsang Souchong in the Garden Terrace of the Four Seasons Hotel here last week. He had just finished instructing the waiters at Four Seasons the art of pouring and serving a light tea.

The hotel offers no tacky tea bags, no instant tea (which Twining calls "nas-tea") but nine different kinds (all R. Twining & Co. Ltd.) of loose tea served in little white pots and a plate of tea time fattings like kiwi tarts, date bread and scones covered in Devonshire cream.

The ultimate tea scoop: What blend of Twining's does the Queen drink?"Can't tell you," said Twining. He expained that revealing such a secret and cashing in on Her Majesty's preference is crass commercialism and would reflect badly on the company. But he did offer his tea table: morning, English Breakfast; lunch, Queen Mary; after lunch Darjeeling; evening, Lapsang Souchong or Prince of Wales (if it issummer), and in the evening Formosa Oolong.

Tea is served at the Four Seasons (28th and Pennsylvania Ave.) every day from 3 to 4:30 p.m. for $3.50 and $4.95.