Cook the pasta in a large saucepan of lightly salted boiling water for 8–10 minutes, or according to the packet instructions, until al dente.
Meanwhile, melt the butter in a large, deep frying pan and saute the mushrooms for 2 minutes over a moderate heat. Add the ham and toss with the mushrooms.
Drain the pasta and tip into the frying pan with the ham and mushrooms. Pour in the cream or creme fraiche then stir until it is heated through, without allowing to boil. Season with pepper and serve at once.