The sauce is the main feature of this creamy dish. Prepare the enriched Alfredo sauce and pour it over boiled fetuccine.
cream (heavy cream)
Parmesan cheese (freshly grated)
Boil the fettuccine in salted water until al dente, this is firm, not undercooked, but not too soft. The key is to use enough water to allow the pasta to have space to move around. That allows even heating and a uniform coating of starch that's boiled out of the pasta. Drain, but don't rinse.
To prepare the sauce, pour half the heavy cream into a bowl, then add the egg yolk and mix well. Pour the other half into a skillet, heated to medium-high. Whisk it well as it begins to boil to prevent curdling, then add the cream-yolk mixture. Keep blending until it's all well mixed. Grate fresh Parmesan and sprinkle onto the mixture, then toss in the parsley.
Drop the still hot pasta over the sauce. Stir until the pasta is well coated with the soft, gooey mixture. Cover and let sit for a couple of minutes.