Bitter penne piccole rigate

Grate the lemon zest, (only use the yellow parts) into a bowl, add the cream and the butter, softened at room temperature and, mixing with a wooden spoon fold in all the ingredients until the consistency of a smooth and blended cream is reached. In the meanwhile cook the penne al dente and mix them with the sauce.Sprinkle with parmesan and arrange the pasta on a serving dish and serve warm.