WHITE VEAL -- milky and delicate, with neither muscle nor fat to mar its perfection. A perfect "10." For years I was convinced that veal scallops and scallopini, born of young calves nurtured on a diet of powdered milk, were the ultimate in haute cuisine and the thing to serve at dinner parties.

Those halcyon days are gone. Veal has so escalated in price that it is hard to justify its frequent use. I've coverted to "chicken scallops." Don't laugh. This seeming culinary paradox is not a crossbreed between a sea mollusk and a barnyard fowl; nor is it some exotic part of the hen's physique.

The words scallop and scallopini have for so long been associated with veal than many innocentrs assume them to be a basic part of the calf's anatomy. Not so! A scallop is the tenderest, leanest portion of any beastie, including fowl. With proper butchering, the result is a boneless, muscle-less, gristleless piece of meat cut thin and pounded to a tender turn. Hence, we create chicken scallops.

Begin with a single (that's half of a whole) boned-out chicken breast. Lay the boneless breast flat on your cutting board. Hold a sharp knife with its cutting edge facing the breast at its thickest side; cut the breast in half horizontally to yield two equal pieces approximately one-fourth inch thick. A particularly thick breast might have to be sliced into thirds.

The next step, "pounding," is a technique used to break down any muscle, tendon or gristle a scallop may have, which then assures a fork-tender, succulent cut of meat. Lacking a classic pounder, any heavy-bottomed implement will do -- the side of a cleaver, flat of a saucepan, even a large book ("War and Peace"). Dampen the base of your "pounder" and grasp it firmly. Continually dampen to avoid wrapping the meat in waxed paper which sticks and tears. Pound the chicken breast with a slight pressure and push forward as you do so. This "down and out" motion will both tenderize and enlarge the breast. One or two swift strokes and your original one-fourth inch slice should be a mere one-eighth of an inch. It is now a carbon copy of the whitest, most pristine veal imaginable!

You can substitute your surrogate chicken scallops in any veal scallop recipe; although the taste is not identical, what difference does it make? Good is good.

Chicken Florentine is the perfect beginning of your romance with poultry scallops: It is economical, relatively low in calories and oh, those golden words, "can be prepared in advance !" ("Florentine" is a code word indicating the use of spinach). This recipe is a casserole of creamy spinach topped with a layer of sauteed chicken and tomatoes, kissed with a quick brown sauce and sharpened with cheese.

Scallops are so thin that they are easily overcooked and subject to toughening. To avoid this, sautee the tender scallops unitl just golden brown, but not yet cooked through (one minute per side, at the most). On reheating, they will cook to completion CHICKEN SCALLOPS FLORENTINE (serves 6-8) 2 pounds fresh spinach or two 10-ounce packages frozen, chopped spinach 3 tablespoons butter or margarine dash of ground nutmeg or 1/8 teaspoon freshly grated nutmeg 1/2 cup sour cream 2whole chicken breasts, boned-out then slit to form 4 single breasts 1 tablespoon butter or margarine 2 shallots or the white part of 1 scallion, finely chopped 1 large garlic clove, finely chopped 4 large tomatoes, skinned and sliced iinto 4 or 5 pieces each 1/2 teaspoon dried basil 4 tablespoons butter or margarine Sauce: 1 teaspoon tomato paste 1 tablespoon flour 1 cup chicken or beef broth, canned or homemade 1/2 cup dry white wine 7 or 8 thin slices Gruyere or Jarlsberg cheese salt and freshly ground black pepper, to taste

If spinach is fresh, wash thoroughly in several changes of water to remove the grit. Tear off large stems and stalks. Place in a large stockpot, cover, add no water and cook over moderate heat for 5 to 6 minutes or until wilted. Once cooked and cooled, squeeze between your hands like a sponge to rid the spinach of all excess moisture. Finley chop.

If the spinach is frozen, allow it to defrost completely, than squeeze it as you would the fresh. There is no need to cook it at this point, since frozen vegetables are already blanched (par-boiled).

Melt the 3 tablespoons of butter or margarine, add the spinach and stir until it has absorbed the fat. Season with salt, pepper and nutmeg. Stir the sour cream into the spinach and spread it into a baking dish that measures approximately 2 inches deep by 8 to 10 inches long by 6 inches wide (or anything it will fit comfortably into).

Cut each single breast in half with the knife held parallel to the cutting board at the thickest side of the breast. Pound until it is of scallopini thinness (1/8 inch). Set aside.

Skin the tomatoes by immersing them in boiling water for 30 seconds to a minute or until their skins wrinkle when touched. Immediately plunge them into cold water to stop their cooking. Cut out the stem and peel back the skin, which should come away easily. Slice into 4 or 5 slices each, crosswise.

Melt the 1 tablespoon of butter or margarine in a large, heavy skillet and cook the shallots or scallions and garlic over low heat until tender but not brown. Add the sliced tomatoes and cook briskly for 3 to 4 minutes. Season with salt and pepper and the basil. Remove tomatoes and set aside. Rinse out the pan in readiness for the chicken.

Season the chicken scallops with salt and pepper, to taste. Make sure they are thoroughly dry. Melt 4 tablespoons of butter or margarine in the skillet. aWhen quite hot sautee them until they are brown but not cooked through on both sides (no more than a minute per side). Remove the chicken and do not clean the skillet.

Off the heat, add the tomato paste and flour to the skillet, stirring them together until well-blended. Return the pan to the heat and cook, gently, until the flour has turned a nutty brown. Little by little, whisk in the stock and wine until the sauce simmers. Season to taste.

Transfer the chicken scallops to the bed of spinach, letting them overlap slightly. On top of them, place the cooked tomatoes, followed by the cheese. Pour the sauce over all. (May be covered and refrigerated at this point. When ready to proceed, remove from refrigerator, allowing casserole to return to room temperature).

It is important that everthing be heated through without overcooking the scallops, therefore you need only broil the chicken Florentine . In order to assure complete re-heating place the casserole a good 8 inches from the broiler so it can remain in the oven 10 to 12 minutes. It should be deep brown on top and bubbling. If you're not quite sure about the temperature of the scallops you may unobtrusively touch one to make certain it is hot.