How to Make Alfredo Sauce from Scratch?

For a great home made Alfredo sauce, melt 3 tablespoons of butter in a saucepan over medium heat. Add 8 ounces of heavy whipping cream. Stir in a pinch of salt, a pinch of nutmeg and a quarter cup each of grated Parmesan and Romano cheeses. Once the cheese melts, add an egg yolk to thicken, stirring to combine.