Remove the outermost leaves from the leeks and wash the leeks under running water to remove any dirt. Cut (the white part only) into thin slices. Cut and remove the casing from the pork sausage.
Heat the oil in a pan over high heat and add the sausage, cooking until it has browned completely. Add the leeks, cook for three minutes, add the white wine and continue to cook until the liquid has been reduced by about half. Adjust the salt and pepper and remove from the heat.
Meanwhile, cook the pasta in a large pot of salted boiling water for the time indicated on the package.
Drain the pasta, dress with the sauce prepared as above and the butter and mix thoroughly.
Top with grated cheese and garnish with parsley before serving.
