Put fettuccine to boil. The sauce will be ready in just five minutes.
Pour cream into a frying pan, add zest. Cook for 3-4 minutes, stirring frequently.
Add butter, melt. Add some parmesan, salt and pepper.
Put the finished fettuccine in a frying pan and stir for literally 1-2 minutes over low heat. If necessary, add a little fettuccine water to thin the sauce.