Langhe, Cuneo province, Piedmont — the plin is specifically Langan and is the pasta shape of the Langhe's aristocratic table. The name comes from the Piemontese verb 'plé' (to pinch). The filling uses the meats of the Langhe's farming tradition.
Agnolotti del plin ('plin' means pinch in Piemontese dialect) are the defining filled pasta of the Langhe hills — tiny, rectangular parcels formed by placing a small amount of filling in a line along a pasta sheet, folding the sheet over, and pinching the dough between each portion to seal and separate them. They differ from ravioli in their closure technique (the pinch, not the cut) and in their filling: roasted meats (typically a mixture of braised veal, pork shoulder, and rabbit, bound with egg and Parmigiano), cooked separately for hours before being used. They are served in the braising broth of the meats used for the filling (in brodo), or tossed with a simple butter-and-sage, or 'al tovagliolo' — literally in a cloth napkin, tossed with nothing and eaten plain with only the pasta's heat and the filling's richness.
Agnolotti del plin al tovagliolo — eaten hot and plain — are a study in the flavour of perfectly braised meat wrapped in almost translucent pasta. The filling is dense, slightly gamey from the rabbit, sweetly rich from the veal, with the depth of long braising. The pasta adds texture without competing. It is one of the most restrained and precise pleasures in Italian cooking.
The filling: roast or braise the meats (veal, pork, rabbit — in the traditional Langhe preparation, the mix uses three meats) until completely falling tender. Cool, then pass through the food mill (not a food processor — the food mill produces the correct texture). Mix with egg, Parmigiano, and nutmeg — the filling should be dry enough to pipe or spoon without spreading. The pasta: thin egg dough (00 flour and eggs, ratio 100g flour per 2 eggs). Roll to nearly translucent (1mm). Pipe or spoon filling in a line, 1 cm from the bottom edge, at 2cm intervals. Fold the pasta over. Pinch firmly between each mound — the 'plin'. Cut along the top edge and between each portion. Cook 2-3 minutes in boiling water or broth.
The 'al tovagliolo' serving (in a napkin) is the Langhe restaurant tradition: the freshly cooked agnolotti are drained and placed on a cloth napkin on the plate, so any remaining pasta water is absorbed. They are eaten with nothing — just the pasta and the richness of the meat filling. The quality of the meat filling is everything.
Filling too wet — it squirts out during the pinch. Pasta sheet too thick — 1mm or less; thicker sheets make the agnolotto doughy. Not pinching firmly enough — the seal opens during cooking. Making them too large — agnolotti del plin are tiny (2-3cm); larger ones lack the elegance of the original.
Oretta Zanini de Vita, Encyclopedia of Pasta; Giorgio Locatelli, Made in Italy