From Ina Garten and Rachael Ray are usually reliable for these types of recipes – 2-4 tbsp butter, 1-1.25 cups heavy cream or half & half, 1 cup parmesan.
Masterclass says you can leave out the cream for the Roman version, and the butter for an easy American one.
Just depends on how rich you want it, and what else you’re using in it. If you’re using half & half, you may want more butter to add more richness, and less if you’re using heavy cream.
https://www.masterclass.com/articles/how-to-make-alfredo-sauce
