Cook fettuccine noodles according to package directions.
Meanwhile, in a large saucepan, melt butter. Then, add cream, salt, and pepper. Bring to a slow rolling boil.
Reduce heat and simmer for 3 to 5 minutes, or until the mixture begins to thicken. (It should be thick enough to coat the back of a spoon.)
Remove from heat and stir in ½ cup grated parmesan cheese.
Drain pasta, reserving a half cup of pasta water. Transfer the drained pasta to a serving dish.
Add alfredo sauce to the dish of cooked noodles. Add pasta water (I used ¼ cup) to reach your desired consistency of the sauce. Toss to combine.
Serve immediately. If desired, sprinkle with additional parmesan cheese and parsley.