ITALY SUPPLIES the dark-shelled chestnuts, variety sativa, that are now heaped in baskets; at supermarkets and produce stalls. America harvested her own crop in the last century from tall trees of castanea that reached 100 feet high; and spread from trunks 12 feet wide. But the native dentata, towering along the entire Eastern seaboard, were felled by a virulent bark disease. "Under the spreading chestnut tree the village smithy stands" is ecological history.

Mercifully, the European strain yields the cherished rich nuts which add aromatic pleasures to sweet palate sensations when roasted or boiled. Chestnuts come from antiquity with their special names in Medieval English. Old French, Latin and Greek.

Though our fresh supply is in the markets only for the late autumn and winter seasons, chestnuts are tasty allies in dishes at any time of the year. In the "off" seasons, jarred and tinned varieties supply menu needs. They are warm and welcome in soups, vegetable dishes, poultry stuffings, or "as is" straight from the shell. Their cold temperature taste in desserts, ice cream variations, chocolaty molds, meringue fillings, defeats the most resolute dieter's regimen.

Removing the chestnut's shell is a tough task, worse than for most in the nutty family. An older method calls for covering them with boiling water and keeping the temperature just below boiling for 20 minutes. The shell and brownish inner skin is removed with a paring knife. Do not try to do more than one pint at a time. There should be no more than two layers of nuts in the pan.

Here is a preferred method which does not soften the inner nut as much: make an "x" with two slits on the flat side using a sharp knife. Cover with boiling water and keep at simmer plus for five minutes. Remove from water a few at a time and peel off shell and skin. With any method, the chestnuts must be hot at the time of shelling/peeling.

Microwave makes it simple. Prepare the nuts by making a 1/2 inch slit on the flat side of the nut. Cover the bottom of a glass pie plate with chestnuts; this will be about one-third of a pound. Set at "high" for eight minutes. The shell will strip off with little effort. The slit is essential, of course, or the oven will be bombarded by exploding chestnuts.

Prepared canned and jarred products pave an easy road to chestnut riches. The popular French company of Clement Faugier (established 1882) has three canned varieties under its white, brown, green and gold label: Entier au naturel (natural, whole, unsweetened in water) in a 10 ounce size; Puree de marron (corn syrup, water, sugar, vanilla chestnuts) in 17 ounce cans.

G. B. Raffetto Company, American purveyors, markets a 10 ounce glass jar of marron pieces in syrup. These items are in the gourmet sections of larger markets, at specialty shops and the more expensive delicatessens. CHESTNUT SOUP (8 servings) 4 cups chicken stock or canned chicken broth 2 cups shelled and skinned chestnuts 1 slice onion 1 1/2 cups cream, medium weight 1/2 teaspoon salt

Bring chicken broth to a boiling point. Add chestnuts and onion and simmer 20 minutes until soft. Whirl in blender to smooth or use food processor. Place in large saucepan. Just before serving, add cream and salt and heat to serving temperature, just below boiling. BRUSSELL SPROUT AND CHESTNUT CASSEROLE (6 servings) 1/3 cup butter 1 pound fresh chestnuts 1 quart brussel sprouts (or two 10 ounce packages, frozen) 1/4 cup water

Butter inside of round two-quart casserole. Prepare chestnuts by shelling and skinning. Set oven at 350 degrees. Prepare brussel sprouts by picking off wilted leaves and cutting the stalk close to the head. Place in saucepan and cover with boiling water; cook at low temperature for 10 minutes. Drain. (Or prepare frozen brussel sprouts according to package directions). Layer brussel sprouts and chestnuts in casserole, starting with sprouts. Dot with butter. Add water. Cover tightly and bake at 350 degrees for 30 minutes. (May be all done in advance except for final time in oven).