THIS MILDLY exhibitionistic meal, composed entirely of filled or stuffed dishes enlivens palates oppressed by deep winter doldrums. It invites admiration, yet is within the capacity of any cook who can read.

The dinner begins with golden brown barquettes filled with an earthy leek pure'e, topped with creamy mushroom sauce, then covered with their own puff pastry lids. The modest puff pastry cases are made effortlessly from the commercial product found in supermarket freezers. Next are lovely, white-fleshed, unfishy whole sea trout that have been boned and stuffed with a feathery mousseline of fresh sea scallops, the stuffing made possible and painless by the food processor. The fish is served with a satiny sauce based on a reduction of the cooking liquids, some cream and a lovely fillip from basil-flavored cider vinegar, or plain cider vinegar reinforced with a pinch of dried basil. Broccoli florets with golden almond slivers give needed texture and a touch of spring green. Dessert is a ring of light, syrup-soaked savarin made from a yeast dough that, according to this recipe, is really a paste and requires no kneading. Its center is occupied by the one fruit that is not a bore at this time of year, fresh pineapple, here macerated with deep, dark rum.

The barquettes are an example of how good-quality, inexpensive frozen puff pastry sheets can change a cook's view of life in the kitchen. The pastry is defrosted and cut into rectangles with a large, sharp knife. The cut should be made cleanly and downward rather than pulled so as not to compress the edges, which would prevent the pastry from puffing properly. There is no need even to roll out the dough. The rectangles are refrigerated until baking time--puff pastry should be kept cold--and before they go into the oven an inner rectangle is incised half an inch from the edges to form the lids.

It is sensible to use boneless fish for company, since whole unboned fish make for messy servings, a pity when the initial presentation is so grand. When you ask at the market to have the fish boned, be sure to say they should be left whole for stuffing. The number you need depends on the sizes available. This varies dizzyingly. Two two-pound trout or four one-plus-pound fish work well, and so would a single four- to five-pound fish, in which case cooking times would be extended. Should sea trout not be available, any fresh and firm white-meat fish can be used. Rockfish (striped bass), sea bass or even rainbow trout are possible substitutes.

No trouble should be encountered with the mousseline if all ingredients, the processor blade and the bowl are well-chilled. I even chill the cognac. Purists recommend pushing the final mousseline mixture through a fine-meshed sieve, a refinement I forgo in the interest of time. Since the foil is removed from the fish 10 minutes before it is ready, the cook will have to bounce up from the table, but only once and briefly, for this maneuver. It shouldn't take more than six minutes to make the sauce.

Flavoring the sauce with basil vinegar proves that in the kitchen, at least, availability is the mother of invention. Its use here is the brainchild of food editor Bill Rice, who one day when we were cooking together decided it would be an interesting addition to a sauce he was inventing. Most herb vinegars are made with wine or rice vinegar, but cider vinegar, with its hint of sweetness, is most successful with basil. It can be made at home when fresh basil is available. Place a loosely packed cup of bruised basil leaves into a jar and cover with cider vinegar that has been brought to a boil. Cap the jar when the vinegar has cooled, and after five days strain the vinegar into a scalded bottle. The vinegar keeps on the shelf indefinitely. The versatile savarin, a yeast dough baked in a ring mold, can be filled with any fresh fruit, with syrup flavorings adjusted to the filling. This recipe is from the newly reissued "The Great Book of French Cuisine" by Henri-Paul Pelleprat. It is different from most savarin doughs, which are dense and bready, and requires practically no effort. The cake is ethereal and so absorbent that it has no difficulty absorbing the warm syrup that is spooned over it. LEEK AND MUSHROOM BARQUETTES (8 servings) For the barquettes:

1 1/3 sheets frozen puff pastry, defrosted for 20 to 30 minutes For the leek filling: 2 bunches leeks 2 tablespoons butter Salt and pepper to taste 1 1/2 cups dry white wine (or flat champagne) 1 cup heavy cream For the mushroom sauce: 1 tablespoon butter 2 tablespoons minced shallots 1/2 pound mushrooms, cleaned and chopped Salt and pepper to taste 1/2 cup heavy cream Strained liquid from the leeks 3 egg yolks

If the puff pastry has been defrosted for more than 30 minutes, refrigerate until the barquettes are prepared. On a lightly floured board and using a large, sharp knife and a straight-down movement, cut the full sheet of pastry, which measures about 9 by 10 inches, into three strips along the lines it has been folded in the package. You will have strips measuring 3 by 10 inches. Then cut a fourth strip from the second sheet. (The remaining pastry can be wrapped tightly and refrozen.) Then cut each strip in half horizontally to make eight pieces measuring 3 by 5 inches. Brush off excess flour and place the pieces upside down on one or two jellyroll pans. Leave ample room between the pieces because they will swell during baking. Refrigerate the pans for an hour or longer. Before placing the pans in the oven, use the tip of a sharp knife to incise a rectangle on each piece of the cold pastry half an inch in from the edges, but do not cut through the pastry. When baked, the inside rectangles will form the lids for the barquettes. Bake in a 425-degree oven 12 to 15 minutes, or until puffed and a golden brown.

With the tip of a sharp knife gently cut the lids free from the bottoms and remove them. Pick out any soft dough from inside the lids and the shells and discard. The barquettes can be baked several hours in advance and recrisped and warmed before they are filled.

To make the filling, discard the green parts of the leeks, split the white parts in half vertically and wash well under cold running water to rid them of all grit and sand. Drain the leeks and cut them horizontally into very fine slices. Melt the butter in a large saute' pan, add the sliced leeks, salt and pepper and cook, covered, on very low heat, stirring often, for about 25 minutes, or until the leeks are soft and transparent. Do not let them color. Add the white wine and cream, cover and cook over low heat for another 20 minutes, stirring occasionally. If the leeks are to be used within an hour or so, set the cover askew on the pan and set aside. They can be cooked a day in advance and refrigerated.

To make the sauce, melt the butter in an 8-inch saute' or frying pan, add the shallots and cook, stirring, over low heat for 3 or 4 minutes. Add the mushrooms, salt and pepper and cook, stirring, over medium heat for another 5 minutes. Add the cream, bring to a simmer, cover and cook over low heat for 10 minutes more. If the sauce is to be used within an hour or so, set the cover askew on the pan and set aside. The mixture can be cooked to this point a day in advance and refrigerated.

Allow about 10 minutes to finish sauce and assemble barquettes. Place shells and lids in a 425-degree oven for 2 to 3 minutes to recrisp and warm. Reheat leeks in their liquid and strain liquid into mushroom mixture. Return leeks to pan and cover. Heat mushroom mixture to boiling and remove from heat. Whisk egg yolks in a bowl and gradually whisk in about 1/2 cup of hot mushroom mixture. Then whisk egg mixture into mushroom mixture. Return to medium heat and, whisking constantly, heat for about 30 seconds. Do not let sauce boil.

To assemble, place each barquette on individual plates, spoon leeks into cases and then spoon sauce over leeks. Place covers on cases and serve. Adapted from "The Three-Star Recipes of Alain Senderens" SEA TROUT STUFFED WITH SCALLOP MOUSSELINE (8 servings)

2 whole sea trout about 2 pounds each, or 4 whole sea trout about 1 1/4 pounds each, boned but left whole for stuffing and heads left on For the mousseline: 1/2 pound very fresh sea scallops, washed, patted dry and refrigerated for at least an hour 1 egg white, chilled 1/4 teaspoon dried basil Salt and pepper to taste 2 tablespoons cognac, chilled 1 cup heavy cream, chilled For cooking the fish and for the sauce: 1 cup dry white wine 1 carrot, peeled and sliced thin 2 medium onions, peeled and sliced thinly 2 tablespoons butter 1 tablespoon minced shallots 1/2 cup heavy cream 1 teaspoon basil-flavored cider vinegar or 1 teaspoon cider vinegar and a pinch of dried basil, or more if needed, to taste

Refrigerate the fish until it is to be stuffed. To make the mousseline, all ingredients must be very cold, including the food processor (or blender) bowl and blade, which should be refrigerated for at least an hour before starting. Process the scallops until they become a smooth paste, stopping the motor once or twice to scrape the flesh down from the sides of the bowl. With the motor running, feed the egg white, basil, salt and pepper through the tube. With the motor still running, pour the cognac and the cream very slowly through the tube. The final mixture should be the consistency of stiff whipped cream. If a blender is used, follow the same procedure but in two batches. Turn the mousseline into a bowl, cover and refrigerate for a least an hour. It can be made a few hours in advance.

Before filling the fish, wash and pat them dry. Spoon equal portions of the mousseline into the cavities and sew closed with kitchen string. The stuffed fish can be refrigerated for an hour before they are cooked. Pour the white wine into a large roasting pan, distribute the carrot and onion slices over the pan and place the fish on the vegetables. Cover the pan with foil and bake in a 425-degree oven. Two 2-pound trout should bake, covered, for 25 minutes; then remove the foil and continue baking for an additional 10 minutes. Four 1 1/4-pound fish should bake, covered, for 15 minutes; then remove the foil and continue baking for an additional 10 minutes. They are done when the fish flake and the mousseline is firm.

Remove the fish with a large spatula to a warm serving platter, blot up any liquid with paper towels and discard the strings. Cover with a tent of foil to keep the fish warm while you prepare the sauce. Melt the butter in a 1-quart saucepan, add the shallots and cook over low heat for 3 or 4 minutes. Strain the liquid from the fish roasting pan into the saucepan and discard the vegetables. Over high heat and stirring constantly, reduce the liquid by one-third. Add the half cup of cream and, stirring constantly, reduce by one-third. Add the basil vinegar or the dried basil plus vinegar and cook for another 2 minutes. Taste and add more vinegar and/or basil, if needed. Pour into a warmed sauce boat and pass separately. BROCCOLI FLORETS WITH ALMONDS (8 servings) 4 pounds broccoli 2 tablespoons butter 1/4 cup slivered blanched almonds

Cut the broccoli flowers plus an inch or two of their tender stems from the stalks and cut into florets, following the configuration of the stems (reserve the coarse stalks for another use). Bring about 5 quarts of water to a boil and cook the florets for 4 to 5 minutes, or until they are just tender. Drain.

While the broccoli is cooking, melt the butter in a small frying pan, add the almond slivers and saute' over medium heat, stirring, until golden brown. Place the broccoli in a warm serving dish and sprinkle with the almond slivers and butter. SAVARIN FILLED WITH FRESH PINEAPPLE (8 servings) For the savarin: 2 to 3 tablespoons softened butter for the ring mold 1 envelope (a scant tablespoon) dry yeast 1/4 cup lukewarm (105 degrees to 115 degrees) water 3 tablespoons sugar 1/4 cup lukewarm milk 3 eggs 2 cups sifted flour 1/2 teaspoon salt 2/3 cup unsalted butter, melted and cooled For the syrup: 1/2 cup sugar 3/4 cup pineapple juice, apricot nectar, peach nectar or orange juice 2 teaspoons lemon juice 6 tablespoons dark rum (Ron Negrita or Myers's) For the filling: 1 pineapple, peeled and cored and the flesh cut into 1/2-inch dice 1 tablespoon sugar 1 tablespoon dark rum 1 teaspoon lemon juice

Grease a 9 1/2-inch (6-cup) ring mold liberally with the softened butter and set aside.

To make the savarin, combine the yeast, warm water and sugar in a large mixing bowl and set aside for 10 minutes to dissolve and activate the yeast. Add the milk, beat in the eggs one at a time and stir in the flour. The mixture will be a smooth paste rather than a dough. Cover tightly with plastic wrap and set aside to rise in a warm place for half an hour, or until the paste has doubled in volume. A turned-off gas oven with a pilot light is an ideal place for the rising. Stir the paste down, add the salt and melted butter and mix well. Pour the paste into the buttered ring mold, cover with plastic wrap and let rise in a warm place for half an hour, or until the paste fills the mold. Bake in a 400-degree oven for 15 minutes, or until a toothpick, straw or cake tester inserted in the center comes out clean. Place the mold on a cake rack for 10 minutes. Run a knife around the inside and outside edges of the mold, place a large plate on top of the mold and invert. The savarin will be upside down.

Make the syrup while the savarin is baking. Place the sugar in a small, heavy saucepan and add the 3/4 cup of whichever juice is preferred along with the lemon juice. Cook over medium heat, stirring, until the mixture comes to a boil. Reduce heat and, without stirring, cook for 5 minutes. Remove from heat and stir in the rum. Set aside while the savarin is cooling on the cake rack.

Spoon the warm syrup evenly over the savarin. Then spoon over the savarin the syrup that accumulates in the center of the ring. When all the syrup is absorbed, place a serving plate over the savarin and, holding it with one hand and the plate on which the savarin is sitting with the other, invert both plates. The savarin will be right side up on the serving plate. The savarin can be covered with plastic wrap and refrigerated for a day.

To make the pineapple filling, combine the diced pineapple with the sugar, rum and lemon juice, mix well, cover with plastic wrap and allow to macerate for a few hours. The filling can also be made a day in advance, in which case it should be refrigerated.

The savarin can be filled several hours before serving. Spoon the pineapple mixture into the center of the savarin and spoon the juices over the cake. Refrigerate and bring to room temperature about an hour before serving.

Note: The savarin can be filled with strawberries macerated in kirsch, in which case kirsch can be substituted for the rum in the syrup. Or the rum-flavored savarin can be filled with rum-flavored whipped cream and served without fruit.