Cook pasta as per directions while making sauce. Saute onion in the butter until transparent. Add proscuitto and cook for 5 minutes. Add peas and cook for one minute (peas should be preheated). Add the cream and cook for another 5 minutes, allowing the cream to thicken a bit. Then add the salt, pepper and nutmeg. Cook pasta to al dente. Drain pasta and place in a warm bowl. Add sauce and cheese and mix well. Serve immediately. Spaghetti or any other pasta can be substituted.