Many Regions in Italy take you to a different style for this basic recipe. In Rome Italy where Grandma was born and raised, this is how she taught us to make it and our family still makes it that was today. Americanized is made with heavy cream.
Here is our basic recipe, we consider Authentic from where it originated.
Hope you like Grandma's version.
Use the pasta machine to makes fresh wide noodles
1 1/2 pound fettuccine cooked al dente and drained ( buy the fresh kind in the dairy case)
2 sticks unsalted butter softened and smashed with the back of a spoon
3 1/4 cups grating cheese around 1/2 pound grated (we like Romano and Parmesan blend)
3/4 cup pasta reserved water or more (note for American version substitute water for heavy cream)
large shreds of Parmesan or Romano cheese for the top
fresh chopped or dried parsley
Smash the butter in a large skillet pan with the back of a spoon the add the warm pasta water, place on low heat just to gently warm the sauce around two minutes . Toss the pasta with cheese in this butter sauce mixture and toss for two minutes to coat. Add more pasta water if needed to make creamier. Garnish with large shreds of grated cheese and parsley. Add salt and pepper as needed.