Boil a large pot of salted water and add the fettuccine pasta.
Cook the pasta according to package instructions until al dente.
In a saucepan, melt the butter over medium heat.
Add the heavy cream to the melted butter and stir well.
Gradually add the grated Parmesan cheese, stirring continuously until melted.
Season the sauce with salt and pepper to taste.
Once the pasta is cooked, drain and reserve some pasta water.
Add the drained pasta to the sauce, tossing to coat evenly.
If the sauce is too thick, add a splash of reserved pasta water.
Serve hot, garnished with chopped parsley and extra Parmesan if desired.