Cook the pasta in plenty of salted water until al dente.
Chop or dice the onions and sauté in the oil until translucent. Drain the tuna and add to the onions in the pan. Sweat briefly. Then deglaze the whole thing with wine. Season well with pepper, salt and the nutmeg, if you like you can also use curry. At the end add the cream, season again to taste.
Arrange the pasta on plates with the sauce and sprinkle with freshly grated parmesan.