Pasta and pesto: taking advantage of basil boom

Pasta, dismissed with a sniff as definitely ''out'' by self-appointed style-watchers last year, is - fortunately - still very much in fashion. But what, you ask, is the well-dressed noodle wearing this year?

This summer it's definitely an Italian pesto-green.

Warm autumn tones of an orange-red, sun-dried tomato sauce promise to do well this fall. For the winter months, a thick white blanket of reduced-cream sauce will be haute couture cuisine.

Spring's arrival will again be heralded by a riot of primavera sauces flecked with pea greens, pepper reds, and squash yellows.

The American Midwest, so often ignored on the pages of W and Vogue, has been well aware of the growing basil-pesto trend. This year Parma, Mich., held its third annual ''Oh, Boy, Basil!'' Festival.

Marilyn Hampstead, proprietor of Fox Hill Farm, where the festival was held on Aug. 5, has followed this greening of the American pasta.

''Of the over 350 different herbs we carry,'' Ms. Hampstead explains, ''basil has become our largest seller over the past few years. It has beaten out thyme and tarragon by far. We now carry 30 different varieties of basil.

''People used to just order common sweet basil, and maybe French fine or dark opal,'' she adds, ''but now they want more exotic ones like lemon or cinnamon as well.''

The main reason for the popularity of this pungent, aromatic herb?

Pesto.

In summer a wave of green pesto starts spreading across the plates, pasta, and palates of hungry Americans from coast to coast.

Ms. Hampstead believes the piccolo verde fino variety to be the best basil for making true Italian pesto. ''It's even sweeter than sweet basil, which sometimes has a slight bitterness,'' she says.

Pesto is an uncooked sauce made of basil, garlic, olive oil, pine nuts, and cheese. Of Northern Italian origin, it can be traced back to the time of the Renaissance.

Its name is a derivative of pestle, as with mortar, and purists say the results are much better when ground by hand with mortar and pestle. But blenders and food processors have taken much of the grind out of this rather tedious work.

Although pasta is the most common medium for this piquant sauce, it is often used to flavor soups, especially minestrone, and sometimes as a topping for potato dishes.

Marcella Hazan, America's doyenne of Italian cuisine, agrees. Speaking from Italy, where she has just finished her yearly cooking classes, she expounded on this wonderful herb sauce.

''Yes, I think piccolo verde is best for the pesto. But basil has a different flavor here in Italy. I have planted the seeds in my home in New York, but basil grown in the States has a slightly minty flavor. Maybe it's the soil.''

For centuries pesto has been kept unrefrigerated in Italian homes. It was simply covered with a thin layer of olive oil and kept in a cool place. Today many people refrigerate or freeze it.

''If you freeze the pesto,'' Mrs. Hazan suggests, ''leave out the butter or cheese and add them later. Cheese tends to get a sharper flavor the longer it is frozen.''

Here is one of her favorite pestos. It is from her book ''More Classic Italian Cooking'' (Knopf, $15).

''The ricotta smooths the pesto out, so it has a less sharp flavor. I like it on potato gnocchi as well as a good-quality pasta or egg noodles. Pine nuts are used in the classic recipe for pesto, but walnuts may be substituted,'' she said. Pesto di Ricotta

2 cups fresh basil leaves, tightly packed

1/2 cup olive oil

3 tablespoons pine nuts

2 cloves garlic, sightly crushed, peeled and cut into pieces

1 teaspoon salt

1/2 cup freshly grated Parmesan cheese

2 tablespoons freshly grated Romano pecorino cheese

3 tablespoons ricotta

2 tablespoons butter, softened

Put first five ingredients in food processor or blender. Process at high speed until blended.

Transfer mixture to mixing bowl. Add Parmesan, pecorino, and ricotta cheeses. Mix thoroughly with wooden spoon.

Add softened butter and mix again until all ingredients have been smoothly amalgamated.

Here is Colette Wismer's winning concoction from last year's festival. First-place winners get $50 in cash in a trophy topped with basil and a pound of freshly cut basil each month for a year. The recipe is included in ''The Basil Book,'' by Marilyn Hampstead (Long Shadow Books, $6.95). Pesto alla Genovese

2 cups fresh sweet basil leaves

1 cup Italian (flat) parsley

1/2 cup Asiago cheese, grated

1/2 cup Romano cheese, grated

12 almonds, blanched

1 tablespoon pine nuts

12 walnuts, blanched

2 cloves garlic, peeled

3 tablespoons butter, softened

1/2 cup olive oil

Place all ingredients except cheese in food processor or blender and blend until fully mixed. Empty in large bowl and stir in cheeses.

Cook one pound linguini al dente. Drain, reserving 4 tablespoons of cooking water. Pour pasta right into pesto. Toss well. Add reserved hot water and toss again. Serves 4 to 6.