When in Rome I always take great pleasure in sampling the delectable variety of frozen desserts sold by street vendors and in charming ice cream bars. The Italians have long been acknowledged as the world's most accomplished ice cream artist.

The art of making flavorful fruit ices passed from the Chinese to the Indians, Persians, Arabs and southern Italians centuries ago. Since the days of the Romans, iced fruit-flavored waters were sough-after and luxurious fare. To keep them cool, the Romans devised a system of preserving ice during the hot summer months.

Catherine de Medici's Florentine cooks introduced ices to the French court in the early 1500s. The English King Charles 1 was impressed with the creations of two Italians who served him ices that the monarch severely warned them never to reveal their secret formulas.

It was a Sicilian, Procopio, who began selling refreshing ices in his cafe in Paris about 1670. Soon thereafter numerous other establishments followed his example and throughout Europe Italian ice experts became status symbols in wealthy homes.

It was not until the 1700s that cream ices were created. Once the consistency of ices had been strengthened with the addition of eggs and creams, the repertory of frozen desserts knew no bounds. Cooks enhanced the basic ice or ice cream mixture with fruit juices, fruit puree, candied fruit peel, liqueurs, nuts, chocolate and other flavorings.

Today in Italy there are two basic kinds of ice cream. Gelati resembles our firm milk or cream type but is exceptionally rich and creamy, made with fresh fruits (bananas, pineapples, wild strawberries, peaches, firm melons, apricot, cherries etc.), or flavored with chocolate, coffee, almonds, hazelnuts, pistachios, egg nog, liqueurs, coconut, mint and even artichokes.

Granite are flavored ices, akin to sherbets, that are slightly granular in consistency, thus the name. They are very easy to make and are not stirred while freezing so they will have fine cystals. Granites may be made with coffee, chocolate, fresh lemon, orange or tangerine juice, or fresh fruits such as apricots, raspberries, strawberries, blackberries or melons.

Because they are particularly refreshing, granite can be served, like sherbets, between courses at a dinner as a palate refresher or a dessert.

Given below are recipes for Italian frozen desserts that can be prepared athome. CITRUS GRANITE (4 to 6 servings) 2 cups water 1 cup sugar Juice of 3 lemons and I orange (1cup juice), strained 2 teaspoons grated lemon rind

Combine water and sugar in a small saucepan. Bring to a boil. Cook rapidly for 5 minutes. Remove from heat and cool. Add lemon and orange juices and lemond rind. Mix well and pour into 2 refrigerator ice-cube trays from which dividers have been removed. Freeze until firm, 3 to 4 hours in freezer top of refrigerator, about 1 hour in freezer. Do not stir while freezing. Serve sherbet glasses. CHOCOLATE GELATO (Makes 1 quart) 3 squares unsweetened chocolate 2 cups milk 2 cups heavy cream 1 cup sugar Pinch salt 6 egg yolks 1 teaspoon vanilla extract

Melt chocolate in top of a double boiler over simmering water. Add milk, cream and sugar and bring to scalding point over simmering water. Whip with a whisk to combine ingredients. Beat salt and egg yolks until creamy in a small bowl. Pour in a few spoonfuls of hot chocolate mixture. Return to double boiler and cook over very low hear, stirring constantly, until mixture coats a metal spoon. Strain. Cool and add vanilla.

Pour into two refrigerator ice-cube trays with dividers removed. Place in coldest part of refrigerator freezer compartment or freezer. Leave until almost frozen solid. Turn into a chilled bowl and beat well with a whisk or beater until smooth and creamy. Return to ice-cube trays and cover with foil. Freeze until firm. SPUMONI (6 servings)

Spumoni can be frozen in a rectangular, melon-shaped or bombe mold. A loaf pan or a square aluminum dish can also be used. This recipe was made in a 1-quart metal mold with a grooved rounded top. 2 cups firmly packed chocolate gelato (recipe above) or good commercial chocolate ice cream 1 cup heavy cream 2 tablespoons sugar 1/4 cup chopped blanched almonds 8 maraschino cherries, chopped 1/3 cup currants, chopped seedless raisins or candied fruit 1/2 teaspoon almond or vanilla extract About 1/2 cup shredded coconut

Line bottom and sides of a chilled mold or dish with ice cream, smoothing out with back of a spoon. Put in freezer to harden; remove and smooth again to spread evenly. Return to freezer until firm. Whip cream until stiff. Fold in sugar, almonds, cherries, currants and almond or vanilla extract. Spoon into ice cream hollow and spread evenly over the top with a knife. Cover with mold lid or aluminum foil. Freeze several hours, until mixture is firm. When ready to serve, unmold on a chilled platter or serving dish and garnish with coconut. CASSATA (6 servings)

Freeze in a dome-shaped metal container with a lid or 1-quart round mold or dish. 2 cups firmly packed, good quality French vanilla ice cream 1 cup heavy cream 1 cup pureed strawberries 2 tablespoons sugar 1 tablespoon kirsch or orange liqueur 1/4 cup chopped walnuts Whole strawberries or grated sweet chocolate

Line bottom and sides of a chilled mold or dish with ice cream, smoothing out with back of a spoon. Put in freezer to harden; remove and smooth again to spread evenly. Return to freezer until firm. Whip cream until stiff. Fold in strawberries, sugar, kirsch and nuts. Spoon into ice cream hollow and special evenly with a knife over the top. Cover with mold lid or aluminum foil. Freeze several hours, until mixture is firm. When ready to serve, unmold onto a chilled serving dish and garnish with whole strawberries or grated chocolate.