DESPITE MYTHS THAT nobody voluntarily comes to Washington in summer, especially to stand in front of a hot oven, from up and down the Eastern seaboard and as far away as Puerto Rico a baker's dozen of professional and amateur pastry makers have gathered at Bethesda's L'Academie de Cuisine. The time is late July, and the master is Roland Mesnier, who for a period of four days will exchange his White House Pastry Chef's hat for the hat of teacher and mentor to the pros.

He explains the premise of the intensive pastry class: "You came here to build a pastry buffet," he says to the assembled disciples. "A buffet," he adds, "like you've never seen before. Forget about being in school. You came here to do a buffet."

A few are in it just for the fun, but most look at this four-day workout as a bit of continuing education at the hands of the master Mesnier. Washington pros include Diane Donnelly, executive pastry chef at the National Gallery of Art, and Gerald Mauri, who recently left his position as chef at Vincenzo's to become executive chef of the soon-to-reopen Old Ebbitt Grill.

This is not the usual collection of cooks. Even the conversation of these people is different uncommon. While they wait for class to begin, two young pastry cooks, Linda Axler of the Four Seasons in New York and Kurt Fischer of the Hotel DuPont in Wilmington, already veterans of many a battle with hot ovens, laughingly compare arms to see who has the most more burn scars.

Two cooking teachers, Shirley Corriher of Atlanta and Rose Levy Beranbaum of New York, who have followed each other in cooking schools around the country, finally meet in the same place at the same time and compare notes. There is a bit of insider gossip and a lot of information being exchanged, mostly about technical things likesuch as the best way to transport wedding cakes and what percentage of fondant to put in marzipan for icing.

In the process of producing this spectacular pastry buffet, scheduled for 4:30 p.m. on a Saturday, four days away, the class will cover the fine points of broiche, croissant, savarin, sponge cake, ladyfinger, puff pastry and other doughs, meringues, icings, fondants, custards, bavarians, buttercreams, fruit salads, ice carving, chocolate coatings, candies and decoration, and sugar work.

The work proceeds in what most nonprofessionals would think of as reverse order. All the decorations--in pulled and poured sugar, in royal icing and in chocolate--will be done first, then the baking will be done, then, just before the buffet is presented, the assembly. all will be put together.

Recipes are provided for nearly everything, but as evidence that these students are expected to be a cut above basic kitchen hack, only the ingedients are listed. Mesnier will elaborate on certain subtleties of technique, but basically these students are expected to know how to put together puff pastry dough.

"Sugar work," a deceptively simple term for the most exacting, creative and painful of all pastry work, is first. Mesnier, the acknowledged master of this artful science, demonstrates. Sugar is cooked with water, poured onto marble, allowed to cool very slightly, then pulled while still at a temperature roughly equivalent to that of molten iron. "It only hurts the first time," Mesnier observes amiably. The class groans, knowing already that it will hurt every time.

As the sugar cools (transferring much of its heat to the hands that are working it), it turns opaque and silky smooth. It is then put into a warm oven to regain its heat, and finally pulled into designs while at a temperature around 200 degrees. Mesnier spins a thin thread out of the sugar glob held in one hand, weaving it in and out of the sugar spokes of the basket as effortlessly as a spider spinning its web. There is absolute, hallowinged silence as Mesnier works. To decorate the basket Mesnier constructs a stunning water lily flower complete with stamens, leaves and stem, also out of sugar.

In the afternoon, when it's the students' turn, blistered fingers and damp hanks of hair being brushed off sweaty foreheads tell a different story. The room is littered with failed rose petals, snapped ivy leaves, recalcitrant stands of inadvertently spun sugar. "Are you having second thoughts?" a visitor asks one blistered participant. "Oh, no," she grimaces. "I really want to learn how to do this." There's a pause. "But here," she offers hopefully and possibly a little mischievously, "Put your hands in this sugar."

Catherine Pressler, a teacher at the school, watches sympathetically. "The first time I worked with sugar I was in a panic," she says, "thinking about how much it was going to hurt. You have to get over your panic."

Only a few sugar petals pass muster, most of those by and those mostly belong to the few students in the class who have already taken Mesnier's 15-week sugar course. Mesnier is not at all the temperamental chef, however, and moves benignly among the novices' work tables, poking here to test temperature, pulling there to demonstrate one more time how stems are made.

Mesnier agrees to a request to demonstrate blown sugar, and gradually a pear emerges from the blob of sugar at the end of his blowing tube. He begins with a new blob and someone asks, "What are you doing now?"

"Just a swan," Mesnier replies, without the slightest snippet of irony.

Thursday finds Mesnier demonstrating how to decorate with chocolate, first tempering it so it will stay glossy and smooth when it's hardened. Lacy chocolate leaves emerge from the end of his paper cornet (a tiny pastry bag), followed by flower petals, miniature ducks and all manner of whirligigs.

The students are set to the production of dozens of tiny pink and white royal icing flowers that will end up decorating petits fours-- petits fours in this case meaningin this case ethereal little cookies, tartlettes and cream puffs, not the rubbery cubes that often curse buffet tables. Pastry-bag-holding techniques are refined and fine points of horticulture are discussed ("I never saw a flower that looked like that," mutters one student, disgusted with her effort). Finally a sufficient quantity of acceptable flowers is produced and set on tiny marzipan bases, then stuck on toothpicks for safekeeping.

Mesnier, satisfied with the effort, tells the professionals in the crowd that they should never be caught without a good supply of royal icing flowers. He muses about his work in restaurants: "On a slow day the chef would say 'Everybody clear the banquettes work surfaces and make roses.' And we'd all make roses. Today if there's a slow day everybody goes home."

Late in the afternoon the students, hardened pros included, are gathered like eager children waiting for Mesnier to produce chocolate liqueur candies, the kind that squirt sweetened liqueur into your mouth when you bite into them. Like ordinary mortals, they want to know how the liqueur gets in there.

Through the magic of sugar crystals, it turns out. Sugar is cooked with water just until it boils, then is poured hot into the liqueur of choice, in this case Grand Marnier. The mixture is then poured into little niches made with the blunt end of a knife in a layer cornstarch that has been dried out for several days in a 100-degree oven. They are then covered with another layer of sifted cornstarch. In about 24 hours, the sugar will have crystallized around the liqueur, forming a crust hard enough to allow the candy to be fished out of the cornstarch, dusted off, then dipped in melted and tempered chocolate.

Back in the pastry kitchen, Mesnier demonstrates the construction of a chestnut-paste chestnut, then asks the students to produce a couple of dozen more, warning them pleasantly, "Make it look good or make it again." The students try and largely fail. "Mine looks like a strawberry," jokes one. When the chef comes back around to check, he pokes through them one by one, throwing about two thirds of them off the tray, hacking the offending chestnuts in half with a large knife. "This one looks like a strawberry," he says. "And this one looks like somebody's nose." Mesnier has the great teacher's natural ability to deliver these epithets without having a roomful of chagrined and tearful students on his hands. They all laugh, then start again on their chestnuts.

Friday the pace quickens, and in short order puff pastry, pa te sucre'e, brioche, savarin and croissant dough are prepared. "I need two quarts of pastry cream! Volunteers!" Mesnier shouts. "Gerry, make the pa te a choux!" Pa te a choux (cream puff) swans are something else that should always be in the freezer, the chef advises.

The smells in the pastry kitchen are devastating by this time, yeasty and sweet and altogether irresistible. Yet there is no wholesale munching going on and very little tasting, aside from a professional finger stuck here and there into the buttercream just to test it. Lemons are being grated, bananas peeled and sliced, gelatin leaves softened, puff pastry dough being turned. And, as in all kitchens, there are disasters too: delicate fan-shaped decorations painstakingly piped out of pa te a choux are breaking apart and being blown to smithereens in the convection oven.

But disasters--at least minor disasters--are part of many a day's work in any kitchen. A big part of Mesnier's task is to teach his students to make the best of things. "A mistake profits the students," he says later. "So I welcome mistakes." He smiles to indicate, however, that his tolerance for mistakes is probably not limitless.

Saturday, the day of the buffet, begins calmly enough with the final preparation of the savarins, brioches and croissants. As the morning wears on, Mesnier is moving into things that aren't listed on any of the handout sheets, yards of plastic film are being used to cover various doughs, a student comes in carrying the magnolia leaves that will be used as decorate ion for the ice carving, and Mesnier is shouting, "We need more puff pastry. Quick! Up! Up!", while he demonstrates how to roll a square of the stuff into a perfect circle without having to trim it.

Plums are sliced for the tart, perfect demitasse cups are constructed entirely of langue de chat batter (except for their baroque chocolate handles) and filled with whipped cream, apples are spread on pastry cream to make the apple napoleon, meringue is transformed into a perfect pineapple to decorate the pineapple cake and through it all one cooking teacher talks softly into her miniature tape recorder, like a commentator at a golf match, getting it all down for future reference.

"We need the torch and a little green marzipan!" the chef calls. Mesnier is going to torch the marzipan, it appears. And sure enough, he does, burning the little marzipan leaf tips just enough to make them look like fall.

Beranbaum of New York and Corriher of Atlanta spend the lunch break discussing egg whites and why they whip or don't whip. Corriher, who makes the food science aspects of cookery one of her specialties, has discovered why egg whites whipped in copper bowls make loftier souffle's. The explanation is long and technical, but her audience is rapt.

By 3:30, an hour before the buffet, the chocolate liqueur candies repose in the sugar basket, the petits fours are arranged, the cakes decorated, the fruit salad made, the pulled sugar flowers in place. Everybody pitches in to clean up the pastry kitchen, and finally the goods are transferred downstairs, carried as carefully as newborn babies. Things have gone well, the only major tragedy being a smashed poured-sugar butterfly, knocked ignominiously from its perch by one careless jostle.

Guests gather to admire, and there is a moment for reflection. Natasha Naunton, a Chevy Chase resident, is not presently in the food business but plans to take what she learned and run with it. Now that her children are growing up, Naunton says, "It's my time. I can do what I've always liked and pursue it as a career."

Rose BeranbaumRose Levy Beranbaum, asked if she got what she came for, returns, as cooks often do, to a food metaphor. "And more," she says. "It's like a big framework of egg whites. You have certain gaps in your knowledge and Roland fills them up."

And the chef? He teaches because he loves it. "If I can do it, I'm willing to show you," he says. A look around the buffet table, laden with more than two dozen platters of complex, beautiful and ultimately delicious pastry, proves his point.

The recipes used in Mesnier's intensive pastry course, because they are designed to be executed in the professional kitchen, are not easily translatable. Below, however, is the recipe for chocolate petits pots used in the course. It illustrates several useful techiques and calls for unusual handling of chocolate. CHOCOLATE PETITS POTS (Make about 8 petits pots) 1/2 cup whipping cream 8 ounces good-quality bittersweet chocolate, chopped 3 cups half-and-half 12 egg yolks 5 ounces sugar

In a small, heavy-bottomed pot, heat cream to the boiling point. Add chocolate and stir off heat until well blended. Return to medium heat and let the mixture cook. It will curdle and look horrible, and eventually start to emit cocoa butter. Keep cooking, stirring constantly and pouring off cocoa butter as it accumulates. After about five minutes the chocolate will begin to leave the sides of the pan and will stop emitting cocoa butter. Do not let it burn. Remove from heat.

Begin heating half-and-half in a saucepan. on the stove to begin heating. Mix Combine sugar with egg yolks in a large bowl and set aside. When half-and-half comes to a boil pour a bit of boiling half-and-half into chocolate mixture to lighten it. Pour the rest of the half-and-half into the egg yolks and sugar mixture, whisking lightly. Then add chocolate mixture to egg yolk mixture and blend thoroughly.

Remove as much foam as possible from top of custard with a strainer. Line the bottom of a heavy, oven-proof pan slightly deeper than your custard cups with a few layers of paper towels. Set custard cups on top of paper towels. Pour custard into cups, straining as you pour, filling cups to the very top or even to overflowing. To remove the last of the bubbles, run a piece of paper toweling across the surface of the cups. Bubbles will go with it.

Fill the baking pan with hot water, as much as you can without overflowing. Cover the baking pan with a large cookie sheet to prevent the tops of the petits pots from coloring. Bake in a 325-degree oven. Begin checking them after half an hour. If the water in the baking pan boils, turn down oven. When done, the petits pots will be just set and will quiver slightly when shaken. Remove from oven and let cool, uncovered, in the water. Refrigerate when cold. Petits pots may be made a day or two ahead of time.

A few miscellaneous tips that will be of use to experienced home cooks:

* The egg whites that whip the best are old egg whites.

* When piping mixtures containing egg whites with a pastry bag, use the largest available opening so as to not deflate the whites.

* When your ladyfinger batter deflates as you pipe it onto baking sheets, as sometimes happens, pipe it into a flat cake shape instead and after baking and cooling, roll it around a filling, jellyroll style.

* When cooking sugar, make sure the burner is bigger than the pot so the sides will heat up and cook any sugar that may be clinging there. Do initial mixing of sugar and water with hands so you can feel any lumps that might remain. To avoid crystallization, rinse sugar from inside sides of pan with fingers, which you repeatedly rinse under cold running water. To avoid crystallization.

* Professionals do not as a rule use sugar thermometers. Instead they test the sugar's stage by dipping their fingers in a bowl of ice water, then quickly into the boiling sugar, grabbing a bit of sugar, then returning to the ice water.