Anyone who has come down from the mountaintop after a five-year sleep would find some great changes in pasta. Oh, other things, too. But the pasta transformation has been spectacular. Linguine with smoked Scotch salmon, caviar and cream. Fettucini with bright green asparagus and shredded snow peas, each silky strand glistening with sesame oil and hot bean paste.

While the trend setters with money to burn are concentrating on the twirly stuff, why not explore some of the stuffed pastas, which have established the noodle's role as a thrifty dish? After all, how many tricks can you name that will turn two cups of leftover roast into a main dish for six . . . or one cup of leftover roast when you add some chopped cooked spinach?

Fresh stuffed pasta has other charms besides thrift. For a dedicated cook, its preparation can be an adventure, a license to invent filling and sauce combinations that have never before been tasted. However, be forewarned that the path from a mound of flour and eggs to a finished aromatic dish is fraught with detours the first couple times around; but know, too, that expertise comes with practice.

One of the best ways to release ourselves from fear and trepidation is to check out four or five recipes in the best Italian cookbooks. Each author has a definite opinion on what makes a pound of fresh pasta dough, from 1 2/3 cups of flour to 3 1/2 cups. The truth is probably somewhere in the middle, but the trick is to stay above it all and cope with whatever you have turned out. The wisest cook will carry on until either the dough or the filling runs out.

Making fresh pasta for the first time from a recipe is similar to learning to swing a tennis racket by reading a book. Recipes run on for yards of anxious detail as the writer tries to give you the lowdown on all pitfalls and successes of his or her pasta-making career. Such earnestness on the writer's part is commendable, but nothing compares with getting up to your elbows in dough.

In the final analysis, each egg will absorb flour according to its whim. One cup of filling should produce four dozen ravioli or agnoletti, but the canneloni will take a little more. Ah, and then there's the sauce.

Does this sound like too much work? It is, but that's not the point. Like baking bread, making filled pasta appeals to the troubled mind. A rhythm develops in the rolling and filling and cutting that is enhanced with a background of Bach or Miles Davis or both. It's the very best way to get through a rainy Saturday morning or a lonely Sunday.

You don't even have to eat it. Filled pasta can be lined up on a cookie sheet and frozen until firm, then wrapped and labeled for a longer stay in the freezer. Dried squares of dough for cannelloni can be wrapped and stored on a kitchen shelf for ages, or at least until some leftover prompts you to fill them.

But lacking leftovers, the following recipe for goulash-filled pasta calls for preparing the stew from scratch. The agnoletti stuffed with chicken and moistened with mushroom sauce is particularly good. And the Korean dumplings came from a restaurant that has a predominately Korean clientele. But the dumplings are judged okay even for foreigners.

FRESH PASTA DOUGH (Makes 1/2 pound) 2 cups unsifted, unbleached flour 1/2 teaspoon salt 3 large eggs Warm water, as needed

If you have a pasta machine, you know what to do, but manual labor has a poetry all its own.

Mound the flour in a shallow bowl. (Working on a flat surface is better when you have more ingredients.) Sprinkle the salt over the flour, make a well in the center and drop in the eggs. Beat eggs with a fork until blended and work in the flour a little at the time until a dough is formed and most of the flour absorbed. If a great deal is still dry, sprinkle the dough with about a tablespoon of water and continue to incorporate the flour.

Knead on a lightly floured surface until the dough is satiny smooth and elastic. For this small amount of dough, it shouldn't take more than 5 minutes. Cover with plastic wrap or an upturned bowl and let it rest at least 10 minutes before rolling out.

For ravioli, divide the dough into 4 pieces, shaping each into similar rectangles to give you a head start on rolling the sheets to the same size. For agnoletti or pasta squares, halve the dough. Using a long, slender rolling pin, roll each segment out into as long a rectangle as possible, but when the dough begins to fight back, cover with a towel or plastic wrap and let it rest another 10 minutes to relax. For ravioli, roll pieces out simultaneously if your work surface is wide enough. Fill as directed in the recipes and allow to dry for 30 minutes, or freeze on baking sheets until firm and store for another day.

CHICKEN AGNOLETTI WITH MUSHROOM WINE SAUCE (6 servings as a pasta course, 4 as a main-dish) 1 recipe fresh pasta (recipe above) Filling: 1 1/2 cups cooked chicken, shredded 1 cup chopped, cooked spinach 1/2 cup each finely minced scallion and minced parsley 1 cup grated parmesan 1 large egg, beaten Salt and pepper Sauce: 1 tablespoon olive oil 2 tablespoons butter 1 large clove garlic, halved 1/2 pound mushrooms, thinly sliced 1/2 teaspoon crushed rosemary 1/2 cup dry white wine 1/4 cup medium-dry sherry 1 cup light cream Freshly ground pepper and salt 1/2 cup each minced parsley and parmesan cheese, combined

Combine filling ingredients, taste and season with salt and pepper. Divide the pasta into 2 equal portions. Keeping one covered, roll out the other until 1/8-inch thick or less. Cut in rounds with a 2 1/2-inch cutter, scalloped if possible, place a scant teaspoon of filling off-center, brush one side lightly with cold water and fold over, pressing firmly to seal in a semicircle. Repeat with the other half of the dough until all the filling is used.

To make the sauce, heat olive oil and butter in a skillet, add garlic halves and saute' until garlic begins to brown. Remove and discard the garlic. Add mushrooms and saute', stirring frequently, until they are lightly brown. Add rosemary and cook 30 seconds. Add white wine and sherry and simmer until reduced by half. Add cream, season and simmer until sauce thickens slightly, about 5 minutes. Keep sauce warm until ready to use.

To finish dish, bring a large pot of water to a boil, add half the agnoletti and cook gently for 5 minutes, or until pasta is al dente. Remove with slotted spoon to a warm oven-proof dish, moisten with a few spoonfuls of sauce, and keep in a 200-degree oven until the second batch is done. When remaining pasta is ready, transfer to the oven-proof dish, top with the rest of the sauce and sprinkle with the parmesan cheese and parsley. Serve immediately.

GOULASH-FILLED PASTA (6 servings as a pasta course, 4 as a main-dish) 1 recipe fresh pasta (recipe above) Filling: 1 pound lean pork, veal or a combination 2 tablespoons lard 1 medium onion, minced 1 small green pepper, finely chopped 1 clove garlic, minced 1 large tomato, peeled, seeded and chopped, or 1 cup canned tomatoes, drained and chopped 1 heaping tablespoon sweet Hungarian paprika Salt and pepper

Sauce: Gravy from the goulash 1 cup sour cream 1/4 cup minced hot cherry peppers or pepperoncini 1/2 cup chopped parsley

Cut the meat into 1-inch cubes. Head the lard in a medium saucepan with a tight lid, add the onion, green pepper and garlic and cook together gently for 3 minutes. Do not brown. Add the meat, tomato, paprika and salt and pepper to taste and stir to distribute the ingredients. Cover tightly and simmer over very low heat for 30 minutes for veal and closer to an hour if pork has been included. Do not remove the lid during the stewing process lest the meat juices evaporate. Test the meat at the end of the cooking time, and continue to simmer, covered, if it isn't done. Taste and add more seasoning if necessary. It should be highly seasoned. Remove with a slotted spoon and chop finely. Reserve gravy.

Prepare the pasta dough, cut it into 4 pieces and pull and stretch each into a similar rectangle. If the work surface is large enough, roll out two at a time, working to keep the shapes even until the dough is 1/8-inch thick or less. Cover one and lightly score the other in 2 1/2-inch squares or mark rounds with a 2 1/2-inch cookie cutter. Place a scant teaspoon of the chopped meat in the center of each square or round. With a pastry brush dipped in water, moisten the edges of the dough surrounding the filling. Top with other sheet of dough and press with the side of the hand to seal the dough securely all around the filling. Cut with a ravioli cutter into squares or with a cookie cutter into rounds, and set aside. Repeat the process with the remaining dough and filling. Allow pasta to dry 30 minutes before boiling. Bring a quantity of water to boil in a large saucepan and cook the filled pasta gently for 5 minutes in two batches. Keep the first ones warm in a warm dish while you cook the others.

To make the sauce, whisk the sour cream into the tepid goulash gravy and fold in the hot peppers. Heat gently, making sure not to let the mixture boil. Top the first batch with half the sauce, and repeat with the remaining pasta and sauce. Bake the dish in a preheated 350-degree oven for 15 minutes, or until piping hot. Sprinkle with the parsley.

KOREAN DUMPLINGS (Makes about 50 dumplings) 1 recipe fresh pasta (recipe above)

Filling: 1 tablespoon sesame seeds 2 tablespoons peanut oil 3/4 pound ground beef 1 clove garlic, peeled and minced 1 teaspoon sesame oil 1 teaspoon salt 2 tablespoons soy sauce 1 large egg, beaten 2 scallions, minced, including the green tops

Sauce: 1/4 cup soy sauce 2 tablespoons white vinegar Peanut oil

Prepare pasta and let rest for at least 10 minutes. In the meantime prepare the filling. Place sesame seeds in a skillet and heat, stirring constantly, until the seeds are a golden brown. Scrape onto a cutting surface and chop the seeds with a sharp knife to release more flavor. (If you have a suribachi, grind them to a paste.) Heat peanut oil in the skillet and saute' the beef and garlic, stirring with a fork to break up the meat, until it has lost all redness. Add sesame oil, salt, soy sauce and 2 teaspoons of the sesame seeds and continue to cook for 30 seconds. Set aside off the fire and when at room temperature, stir in the beaten egg and minced scallion.

Divide pasta into two pieces. Cover one with the towel and roll out the other until it is about 1/8-inch thick. Cut in 2 1/2-inch squares using a ruler to keep them uniform. Fill immediately with a scant teaspoon of the filling set slightly off-center, brush one side very lightly with water, and fold in half over the filling. Press edges together securely. Repeat with the remaining dough. If you have leftover pasta, chop it into tiny squares, dry and store in a covered container for soups.

Bring a large kettle of water to a boil and add half the dumplings. Simmer for 3 minutes and drain well. Place the dumplings on a warm platter in a 200-degree oven until they are all cooked. Heat enough peanut oil to cover the bottom of a large skillet (about 4 tablespoons) and saute' the dumplings on both sides until they are golden brown. You will have to do this in 2 or 3 batches, adding more peanut oil as needed. To make the sauce, combine the soy sauce, vinegar and remaining sesame seeds. To serve, arrange the fried dumplings on a warm plate and divide the dipping sauce between two small dishes.