NO CREAM in Alfredo, at least not a true Alfredo, at least not the Alfredo that Mary Pickford and Douglas Fairbanks fell in love with on their honeymoon when they dined frequently at Alfredo's in Rome.
The "real" Alfredo is just an al burro, with extra technique. I.e., you really, really, really and truly cream the butter; then really, really, really and truly incorporate the cheese. The heat of the fettuccine and perhaps a splash of the cooking water is the only cooking it gets. The "sauce" and the pasta should always be mixed tableside.
The creaming and incorporation of the cheese have to be so thorough that the sauce is an emulsion which holds together even as it melts.
The story of that Alfredo, from the lineal descendant of the Roman restaurant is all over the net. So is the recipe, for that matter.
It's a very matrimonial story, romantic really. To cut it short, when young Signora Alfredo got pregnant for the first time, she had a hard time holding anything down. Signor Alfredo made the most digestible and calorie laden thing he could imagine; and she liked it!
Not too long afterwards, the PickFair couple spent part of their honeymoon (the most well-covered event to that point in the century) in Rome. They ate at Alfredo's and fell in love with the dish and the Alfredos; and continued to eat there frequently. When the couple left Rome they gave Alfredo a pair of golden spoons for the tableside mixing.
I went to Rome for the first time in 1963, and was taken to eat at the famous Alfredo's. We had fettuccine (or was it tagliatelle?) Alfredo and I still remember those spoons.
Maybe there's another Alfredo somewhere else who did use cream. Quien sabe? No one appointed me the keeper of Alfredo authenticity but I do love the original dish and the associated story.
I've done the popular US variations with cream, and even with cream and egg, and while they have their charms, neither can hold a candle to the original. The best you can say is that they're less effort if you're not using a food processor, and they're stable too.
On the other hand, I've done some lighter plays on Alfredo like whipping cream almost to the butter stage, whipping a dry cheese like cotija in it, and melting that in the pasta -- which have worked very well.
BDL