Aligot depends on tomme fraîche, an unripened, springy curd made on the Aubrac plateau precisely for this dish; aged cheese won't give the same long, elastic stretch.
Aligot is mashed potato beaten vigorously with fresh Tomme cheese, garlic, and butter until it turns into a smooth, elastic mass that stretches like taffy when pulled. Market stalls and fairs on the Aubrac plateau serve it ladled straight from huge pots, still being stirred.