In Italy a good way to explore the local cooking is to sample appealing snacks at sidewalk cafes, rustic trattorias, street stands and stand-up espresso bars. Flavorful foods, known as passatempi (pastimes) and eaten any time of the day or night, are particularly good while strolling along the streets. For me, the best treats are those made with Italian cheeses.

The art of making cheese has long flourished in Italy. Ancient Romans created a varied repertoire of superb cheeses and introduced cheese-making techniques to other Western European countries. In modern times the Italians are outranked only by the French in the choice of innovative cheeses.

Cheese is widely used in Italy as a finale to meals and it also plays an important role in the cuisine. It is wrapped in meats, hidden in breads, concealed in croquettes, bound with pastry and, of course, is essential to pizzas.

For cooking, the Italians rely primarily on hard Parmesan, soft ricotta, and semisoft, elastic mozzarella. The latter is popular for snacks and sandwiches. Originally a Neapolitan cheese made from buffalo's milk, mozzarella is now generally prepared from cow's milk. It should be whitish, soft and slightly moist. It comes in a creamy ball or round packet that was once called "buffalo egg." Because of its delicate flavor, some mozzarella snacks are accompanied by a highly seasoned anchovy-butter sauce.

One of the most popular. Italian snacks is crostini, a canape or small open-faced sandwich made with sqaures, rounds or fingers of firm or stale white bread fried in butter and oil or toasted on one side and spread with various toppings. Other than snacks, crostini may also be served as appetizers, with soups or as luncheon dishes.

Originally from Naples, but now popular throughout Italy, crostini are most often made with slices of mozzarella and such garnishes as herb-flavored tomatoes and green peppers or an anchovy-butter sauce. Other Italian toppings are truffles and Parmesan cheese, fish mixtures and herb-flavored chicken livers. An old-time Roman favorite was bone marrow.

Crostini di provatura, a specialty in nearly every Roman trattoria, is traditionally made with a small, fresh, soft buffalo milk cheese called provatura. Because it is difficult to obtain nowadays, mozzarella is often substituted.

Another variation of crostini is made with slices of stale bread that are dipped in beaten egg, topped with slices of mozzarella and grilled until puffy and golden.

Romans are also fond of a snack or antipasto that is like a croquette made with rice, meat and flavorings, with a piece of mozzarella or provatura in the center. It is called suppli al telephono because as the cheese melts during the cooking it makes long strings or threads when eaten. Hence the Italians named the dish "telephone-wire croquettes." Other favorite street snacks of Rome are spiedini (Italian for skewers) on which meat balls, shrimp or other foods are fried or grilled. The most popular variety, called spiedini alla Romana, is made simply with mozzarella squares interspersed with cubes of bread and brushed with an oil-anchovy sauce.

Early cooks of Naples created two other types of snacks: calzone, baked circles or crescent-shaped turnovers made with leavened dough and filled with mozzarella, cheese, ham, herbs; and sometimes tomatoes and anchovies. Calzone, a gastronomic relative of pizza, may be fried in oil or baked. Mozzarella in carrozza, mozzarella in a carriage is actually a fried cheese sandwich that can be prepared in various forms, all of which are good as snacks or light entrees.

Given below are recipes for three Italian cheese snacks. MOZZARELLA IN CARROZZA

(4 servings) 1/2 cup butter or combination of butter and olive oil 4 flat anchovy fillets, drained and minced 1 tablespoon fresh lemon juice 8 slices firm white bread 4 thick slices mozzarella cheese 2 eggs 3 tablespoons milk Salt, pepper to taste Olive oil and/or butter for frying

Heat butter or butter and oil in a small saucepan. Add anchovies and lemon juice. Keep warm. Remove crusts from bread and top 4 slices with a slice of mozzarella. Top with remaining slices of bread to form sandwiches. Combine eggs, milk, salt and pepper in a shallow dish. Dip sandwiches in mixture to coat well on both sides. Fry sandwiches in heated oil or butter in a large skillet on both sides until golden and mozzarella begins to melt. Remove and drain on paper towels. Serve hot with anchovy sauce.

Note: To make appetizers, cut bread into 3-inch rounds or squares and serve with or without a little sauce. ROMAN SKEWERED BREAD AND CHEESE

(6 servings) 1 long loaf Italian bread 1 pound mozzarella cheese 3/4 cup butter or margarine 10 flat anchovy fillets, drained and minced 1 tablespoon fresh lemon juice

Cut bread into sliced about 1/2 inch thick. Trim off crusts to form squares. Cut cheese into slices the same size as the bread and about 1/4 inch thick. Thread bread and cheese alternately, beginning and ending with bread, on small skewers. Push together. Place in a pie plate or shallow baking dish. Cook in a preheated 450-degree oven about 15 minutes, turning once, until bread is golden and cheese is melting. Meanwhile, heat butter, anchovies and lemon juice. Spoon over hot bread and cheese. Serve at once.


(Makes about 13) 1 package (6 3/4 ounces) pizza flour mix or equivalent amount of pizza dough About 36 think slices prosciutto or cooked ham, cut 2-by-2 inch About 18 think slices mozzarella, cut 2-by-2 inch 2 tablespoons dried basil or oregano Salt, pepper to taste Olive or vegetable oil for deep frying

Prepare pizza dough according to package directions. Roll out on a floured board as thin as possible and cut into 4-inch rounds. Place a slice of prosciutto or ham on one half of each round. Top with a slice of mozzarella and another of proscuitto. Sprinkle with a little basil or oregano, salt, pepper and olive oil. Dip tip of a finger in cold water and run around edge of each circle. Fold other half of round over filing and press edges to close firmly. Deep-fry a few at a time in hot deep fat (375 degrees on frying thermometer) until golden and crisp, or cook in a preheated 375-degree oven about 20 minutes.If fried, drain on paper toweling. Serve hot.