Start by boiling a big pot of water for the pasta with the rock salt. When it boils add the pasta and cook as per the instructions
Whilst the water boils in a pan add the butter and when melted add the mushrooms and cook for 5 minutes or so until they shrink in size and start to brown. Remove from the pan and set aside.
In the same pan add some butter and cook the thinly chopped leeks for about 10 minutes. Use the wine to cool down the pan and stop the leeks from burning. When they are cooked add the mushrooms and the stir for a couple of minutes. Turn the heat right down and add the cream. Don't let the cream boil if you can avoid it.
When the pasta is ready keep some of the water from cooking aside, drain it and add the pasta to the pan. Mix well and add the grated parmesan. If it looks too thick add some of the water from the pasta and mix well. Serve hot with a sprinkle of parmesan on top
