Cook the garlic in a medium hot skillet, but don't brown it too much.
Add a splash of white cooking wine.
Add about half a cup of half-and-half.
Add a tablespoon of Parmesan cheese, salt, and pepper.
Bring the sauce to a simmer.
Drain the cooked pasta and add it to the sauce.
Add the green onions and parsley.
Separate an egg yolk and stir it into the sauce to thicken it, being careful not to boil it.
Serve the fettuccine alfredo, optionally with blackened chicken or shrimp, and sprinkle more Parmesan cheese and parsley on top.