Here are three recipes that make use of port wine. Port, made in Portugal, is much admired by French chefs as a flavoring agent for sauces and is so used in the first recipe. It's compatibility with peaches was dicovered accidently and made enough of an impression to inspire a variation using many of the same ingredients.

Port is a splendid drink either by itself or with Stilton or another fine blue cheese. As with unfortified wine, it is only common sense to marry food with a Port that is good enough to drink on its own. While vintage Port can be quite expensive, fine ruby and lawny Port blends are available at moderate prices. Wines designated only for cooking should be left in the shelf at the store. CHICKEN TARRAGON

(2 servings) 2 large chicken breast halves 3 cups chicken broth or bouillion 1 bouquet garni including 1/4 teaspoon thyme, 1/2 teaspoon tarragon, 1 bay leaf and 4 or 5 sprigs parsely 6 mushrooms, cleaned and quartered 2 1/2 tablespoons butter 1 1/2 tablespoons flour 1/2 teaspoon dried tarragon or 1/2 tablespoon fresh, chopped 2 tablespoons ruby Port Salt and pepper to taste 1 bag (10 ounces) fresh spinach or 1 box frozen

Bring chicken broth to a boil with the bouquet garni. Add chicken pieces and poach at a simmer until just cooked, 18 to 20 minutes. Add mushrooms for final 5 minutes. Pour off and reserve liquid. Peel skin from chicken and slice meat from the bone.

Meanwhile wash spinach, pull off overlarge stems and cook in a covered skillet without additional liquid until wilted. When cool, squeeze out liquid.

Melt 1 1/2 tablespoons butter in a saucepan. When it bubbles, add flour and cook for a minute. Pour in 1 cup of broth and stir until a sauce forms. Add about 1/4 cup more broth, the crushed or chopped tarragon and simmer for 10 to 15 minutes. Add cooked mushrooms, Port and season with salt and pepper. (The recipe may be done ahead to this point.)

Grease the bottom of a small oven-proof casserole with remaining tablespoon of butter. Spread spinach over bottom, season and cover with chicken slices. Pour sauce over all and reheat in a 325 - degree oven for 12 to 15 minutes or until heated through. PEACHES IN PORT

(6 to 8 servings) 6 ripe peaches, still firm 4 tablespoons granulated sugar, or to taste 1 tablespoon lemon juice 1/2 cup Port wine 1/2 cup whipping cream 1 tablespoon confectioners' sugar

Dip each peach briefly into boiling water and peel away skin. Cut flesh from pit into a bowl in even slices. Sprinkle sugar atop peaches and mix in. Add the lemon juice and port. Chill or 1 to 3 hours. Taste liquid and adjust seasoning as desired with Port or lemon juice.

Just before serving, whip the cream stiff with a pinch of salt and the confectioners' sugar. Spoon peaches and some of juice into individual serving bowls. Top with dollops of whipped cream. BLENDER PEACH DESSERT

(4 servings) 4 large peaches 1 1/2 tablespoon sugar, or to taste 1/2 tablespoon lemon juice 3 tablespoons Port wine 3/4 cup chilled plain yogurt Dip each peach briefly into boiling water and peel away skin. Cut flesh from pit into a bowl in even slices. Sprinkle sugar atop peaches and mix in. Add the lemon juice and port. Chill for 45 minutes to 1 hour, stirring from time to time. Place contents of bowl in a blender with yogurt. Blend briefly, about 30 seconds, trying to leave bits of peach. Pour into individual dishes and serve.