Por boiling water over the dried mushrooms and leave them to soak for 15 minutes.
Meanwhile melt the butter and saute the other mushrooms until well coloured.
Drain the wild mushrooms, reserving the soaking liquor, then add to the pan and cook for a minute. Pour in the soaking liquor and the stock. Cook until the liquid is reduced by two thirds.
Add the cream and simmer until the sauce coats the back of a spoon. Taste and season.
Cook the pasta in boiling salted water until al dente. Drain and dress with the sauce, then serve with the grated parmesan.