Clean the pumpkin, removing the rind, the seeds and the filaments, rinse and dry it then chop it up into big chunks. Peel the onion, rinse it and slice it into thin segments. Reduce the amaretti into powder.Heat 30 g of butter, in a pan, add the onion and fry until soft but not golden, add the pumpkin segments and brown briefly, mix with a wooden spoon. Season with salt and pepper, cover the pan and simmer for 10-15 minutes over a medium heat, adding a few spoonfuls of water from time to time.Add the cream, the amaretti and mix the ingredients well until folded in well. In the meanwhile cook the pasta in plenty of boiling salted water. Drain it al dente with the pumpkin sauce, add the leftover butter and the parmesan. Mix and serve warm.