After centuries of seemingly undiminished popularity, the egg has come upon hard times. Celebrated for its artistic shape, admired for its nutritive value and versatility, fountain of jokes as well as culinary joys, the egg led a charmed life until cholesterol marched so forcefully into our collective consciouness. Eggs contain cholesterol and cholesterol, according to dominant medical theory at the moment, is dangerous. It may contribute to heart disease. Therefore, Americans have been advised to cut back on eggs, on butter, on cream and several other foodstuffs, once thought to be essential ingredients in any recipe for the gastronomic good life.

French chefs shrug (something all Frenchmen seem to-do with flair) and keep on making their favorite sauces and pastries. La nouvelle cuisine has sworn off flour and calories, but it hasn't abandoned eggs. Michael Guerard's most celebrated dish may be scrambled eggs served in the shell topped with a dollop of caviar. Paul Bocuse and Roger Verge opened a gala dinner for 100 in Los Angeles last month with scrambled eggs in oyster shells (paired with oysters veloute in egg shells).

But Americans are not so blase. Egg sales are down. Egg production is down.

One could pick nits, and point out that only a small percentage of the population actually is plague by excessive cholesterol; that in cautioning everyone away from eggs, nutritionists, and doctors are cutting out one of the best, most readily available and cheapest sources of protein from American diets.

The argument over cholesterol's role in heart disease won't be settled for some time. In the meantime, as a few eggs are allowed in all but the most stringent diets, perhaps a plea to treat them with respect is in order. Even in small quantities, well-prepared egg dishes can bring considerable pleasure. Badly done, egg chopped up in floury white sauces. Ugh!

Think of the travesties that are served daily - hard and papery fried eggs, rubbery and dry, scrambled or "hard-boiled" eggs, eggs chopped up in floury whites sauces. Ugh!

Shoppers recognize an egg's delicacy. Just watch them pulling open cartons in the market to be sure there are no cracked or broken ones inside. If that concern is carried to the stove and combined with a few elementary cooking techniques, Egg Heaven can be the reward.

To begin: brown or white? The distinction is meaningless. Eggs will keep better if they are stored in the carton instead of in those cute containers in the door of the refrigerator. An extra large egg will weigh about 1/2 ounce more than a small egg, but substitute 2 small for 1 large in recipes. Very fresh eggs are best for poaching, but older eggs are more satisfactory for "boiling" (properly called "hard-cooking" because the water should not boil, only simmer, lest the eggs become tough).

Freeze egg whites. They love it. A one-cup measure will hold 8 to 10 whites, so figure accordingly when using thawed white. Unbroken yolks may be completely covered with water and stored in the refrigerator. It take 12 to 14 to fill a one-cup measure. Egg whites should be at room temperature before heating; they will rise faster and higher. Beating by hand in a copper bowl is best, for a person with strength and patience. Lacking either, or both, add a little cream of tartar to the whites in the mixer. The chemical helps stabilize the whites. Yolks do their work either warm or cold, but cook (curdle) as the boiling point is approached.

Cooking eggs. Grimod de la Reyniere, the French tastemaker who flourished early in the 19th century, recorded 685 ways to prepare eggs, and that was nearly two centuries ago. But what good is elaboration if the basics are ignored?

How easy is "boiling" an egg? Not very, if one judges the results of both amateur and professional cooks. Of the multitude of methods, the following my choice of soft-cooked eggs:

Take eggs directly from the refrigerator and place in a pan. Cover by at at leastan inch with cold tap water. Over high heat, with the pan uncovered, living the water to a boil. Remove pan from the heat, cover and leaver for one to three minutes, depending on how soft a yolk is desired. Piunge in cold water to make shelling easier and serve immediately.

For hard cooked eggs, follow the same procedure but leave the pan covered for 10 minutes (semi-soft yolk) to 15 minutes (solid yolk).

Fried eggs? Not too much grease and not too much heat. Celiophane edges aren't Mother Nature's idea of good cooking. French cooks often sprinkle some melted butter atop the eggs in a hot pan and bake them in the oven. They emerge with a skiny-looming top. Thus the name oeufs miroir. Eggs cooked this way in often are served with a sauce, or they may be baked in cream.

It's not difficult to scramble eggs property. The problem is to convince otherwise logical and intelligent people that properly scrambled eggs are not going to hurt them.

Doctrinaire it sound, but scrambled eggs should be soft and creamy. For two or three servings, take 6 eggs and break them into a bowl with 3 tablespoons of cream and 2 or 3 grinds of pepper. Heat 3 tablespoons of butter in a frying pan over low heat. When the butter begins to foam, add the eggs and stir with a wooden spoon or rubber spatula until the eggs are congulated but still soft. This can take 8 to 10 minutes. (Some cooks prefer to 'scramble' their eggs in the top of a double boiler.) Stir in another tablespoon of butter and 1 of cream off the heat. Season with salt before serving with toast or English muffins.

Various tidbits - mushrooms, bacon or ham, fresh herbs - may be added to these eggs. Best of all, should a fortune come your way, is a generous dice of fresh black truffle warmed separately in butter.

Not content with mere greatness, a nervous scrambled egg cook one day invented the omelet. All the experts say it's easy, but it does take practice. A modern convenience, the non-stick pan, will lessen the cook's anxiety though it may produce the beautifully light brown exterior imparted by traditional omelet pans. If the pan at hand is cast-aluminum, clean it with coarse salt and oil. Don't was it.

Begin with 3 eggs. Break them into a mixing bowl, add a tablespoon of water and any herbs or seasonings desired. Beat lightly. (Fillings should be prepared separetly and added just before the omelet is rolled.) Heat the pan.

Add a tablespoon of butter and wait until it has just passed the point of bubbling and gives off a nutty odor. Removed pan from heat immediately, pour in eggs and return to high heat. With one hand shake the pan gently by the handle. With the other stir the eggs with a fork in a circular pattern. When the omelet has set - it should take no more than 30 seconds - start rolling the omelet (a rubber spatula is a good tool) from the side nearest the handle. Reverse grip on the handle and tip it forward a plate as the rolling progresses and serve at once. Wipe out the pan with a paper towel and make as many more omelets as are needed.

Souffles and omelets require one similar quality in a cook: lack of fear. Once begun, the omelet procedure should be followed through quickly. Doubt or hesitation leads inevitably to failure.

Like a baby, the souffles is much hardier than its appearance. Fold in the whites quickly, leaving some patches unmixed if they are stubborn. Once the souffles is in the oven, it isn't necessary to walk around in bare feet for fear of jarring it. If it is rising unevenly, open the oven door and move it. Though it files in the face of our love of bigness, height is not the true judge of a fine souffle. Texture is. A slightly runny center is quite acceptable, but a scrambled egg interior is not. In fact some French cooks undercook a souffle in order to use the still-liquid center as a kind of sauce.

There is a souffle among the recipes that follow. Perhaps, in addition to the directions, it should be ordered "medium rare" or "medium well." SHRIMP SOUFFLE (4 servings) 1/2 pound small shrimps, or larger shrimps cut into pieces 1 cup milk 3 tablespoons butter or margarine 2 generous tablespoons flour 1 ounce gruyere cheese, grated (about 1/2 cup) 4 eggs, separated 1/2 teaspoon paprika Salt and pepper

Grease a 1 1/2 quart mold. Preheat oven to 425 degress. Cook shrimps in milk (or heat in milk if shrimps are precooked). Strain out shrimps. Melt butter in a saucepan, add flour and stir with a whisk for at least a minute without coloring the flour. Add milk and stir to make a thick sauce. Off the heat, beat in egg yolk - one at a time - and grated cheese, then the shrimps. Season with paprika, salt and pepper.

Beat egg whites stiff. Reheat sauce briefly, stir in about a quater of the whites, then quickly fold in the remainder. Pour into the mold, level the top and bake for 15 minutes. Serve at once. MY FAVORITE EGG SALAD (Makes about 2 cups) 6 hard-cooked eggs 1/2 rib celery, finely diced 2 teaspoons Dijon-style mustard 1 teaspoons dried tarragon, crushed 1 tablespoons chopped fresh parsley 1 teaspoons celery seeds 2 tablespoons mayonnaise 2 tablespoons sour cream Salt and pepper Lemon juice Peel eggs and place in a mixing bowl. Crush or cut up with two knives. Add remaining ingredients. Mix well, adjusting seasoning to taste with salt, pepper and lemon juice. Spread on toast rounds or in small pastry shells as an hors d'oeuvre or use in sandwiches. MUSHROOMS AND EGGS (Serves 4 as appetizer or luncheon main course) 6 hard-cooked eggs 1 tablesspoon butter 1/2 teaspoon mild curry powder 1/2 cup heavy cream

1 tablespoon fresh chives, chopped 1/4 pound large mushrooms, sliced thin 1 teaspoon lemon juice Salt, pepper Chopped parsley

Peel and slice the eggs and arrange them on a heat-resistant serving platter. Melt butter in small saucepan. Add curry. Stir over heat for 1 minute without burning curry. Pour cream into the pan and heat through, then add chives and mushrooms slices. Cook, partly covered, for 6 to 8 minutes over low heat. Remove mushroms with a slotted spoon and spread them over the egg slices.

Increase heat to reduce the sauce by about a third. Add lemon juice, salt and pepper. Taste and adjust seasoning, then pour hot sauce over eggs and mushrooms and garnish with parsley. The dish may be held in a warming oven. If so, add parsley only just before serving. BURGUNDY - STYLE EGGS(4 or 8 servings) 8 eggs 1/2 cup white vinegar 1/2 stick (2 ounces) butter 1 large onion, sliced 1/4 cup flour 1 bottle red burgundy wine 1 head garlic, unpeeled but cut in half 1/4 teaspoon dried thyme 2 bay leaves 5 or 6 sprigs parsley 1 teaspoon salt 1 teaspoon Dijon-style mustard 1/4 pound mushrooms, quartered Juice of 1 lemons 1/2 pound sinb bacon, cut into 1/2-by-1/2-1 1/2-inch julliane 16 small onions, cooked until just tender and peeled 8 slices state French bread, rubbed with a clove of garlic Salt and freshly ground pepper

The eggs may be ponched a day ahead or in the morning of the meal. Heat water with vinegar - but no salt - to a boil. Slide eggs into water and poach until firm but still runny in the centers. Transfer to cold water to stop cooking. Trim edges with a knife and refrigerate, covered with cold water.

Melt butter in a heavy saucepan. Add onion and cook until soft. Sprinkle on flour. Cook and stir over low heat until flour is a cocoa brown. Stir in the wine, bring to a boil, then add a cheesecloth bag containing the head of garlic, thyme, bay leaves and pareley. Simmer, partially covered, for an hour. Lower heat and move pan so only a corner is over the flame. Remove skin that forms on surface serveral times during next 15 minutes. Pour sauce through a sieve, stir in salt and mustard to taste and net aside.

Cook mushrooms in a small pan with 1/2 tablespoon each of butter and salt, plus juice from the lemon and enough water to cover bottom of the pan. Cover pan and bring to boil.Leave on heat 2 minutes longer, then allow mushrooms to cool in the juice. (Juice may be used in sauces or soups.)

Blanch bacon for 5 minutes in simmering water. Drain and dry. Prepare onions and croutans.

Saute bacon until crimp in frying pan with a tablespoon of butter. Remove. Saute onions in drippings until they begin to brown. Reserve. Fry brend in dripping or olive oil to brown on both sides.

The dish may be prepared ahead to this point.

To assemble, reheat sauce and bring a low pan filled with water to a simmer. Place bread croutons on plates, portion out onions, mushrooms and bacon pieces and warm in oven. Place eggs in water only to heat through. Drain, set on croutons and spoon hot sauce over all. Serve at once. DESSERT OMELET WITH RED CURRANT SAUCE (4 to 6 servings) 4 eggs, at room temperature, separated 1 tablespoon milk 1 tablespoon sugar Pinch salt 1/4 cup red currant jelly 1 tablespoon kirsch

Preheat oven to 400 degrees. Mix egg yolks with milk, sugar and salt. Heat jelly with kirsch in a saucepan. Beat whites until firm but not dry. Fold whites into yolk mixture while butter is melting in an omelet pan. After butter bubbles, add egg mixture to pan and smooth the top. Cook over medium heat 4 to 5 minutes, or until golden and puffed. Place omelet pan in oven and cook another 5 minutes. Slide onto a plate, top with sauce and serve. SNOW EGGS WITH CUSTARD SAUCE (6 to 8 servings) 2 cups milk 1 vanilla bean, split, or 2 teaspoons vanilla extract 6 eggs, at room temperature, separated 1 cup granniated sugar

Bring milk and vanilla bean to a boil. Cover pan and let milk steep for 10 minutes. Remove vanilla been. Of using extract, and vanilla later.) Pour 3 inches of water into a frying pan and heat with 6 tablespoons sugar. Whisk or beat egg whites until nearly stiff. Gradually beat in 4 tablespoons sugar.

Use two large spoons to form the meringue into egg-shapes. Poach these "snow eggs," 6 or so at a time, in the hot - but not boilling - water. Turn once during cooking, then set aside to drain and cool on towels.

Reheat milk. Whisk the egg yolks in a bowl, then stir in a warm milk. Return to saucepan and whisk gentle until it thickness into a custard sauce. Off the heat, and vanilla extract.

The sauce and eggs may be covered with plastic wap and stored in the refrigerator until needed. To serve, place eggs in a serving bowl and gently pour sauce around and over them.

To prepare a caramel topping (optional), place remaining 4 tablespoons sugar and 1 tablespoon water in a heavy-bottomed pan. Place over high heat. Don't stir. When sugar melts and caramelizes, pour in 1/4 cup warm water and stir off the heat until all the carmel has dissolved. Cool and pass in a sauceboat.