1cupfreshly finely grated parmesan cheeseplus more for serving
Kosher salt and freshly ground pepperto taste
¼cupchopped fresh parsley
Red pepper flakesto serve, optional
Bring a large pot of salted water to a boil. Cook the fettucine according to package directions.
Meanwhile heat the milk and cream in a saucepan just until warm; don’t let it come to a simmer (you can also do this in a microwave).
While the milk is heating, melt the butter in large deep skillet over medium heat, then add the garlic cloves and stir for 1 minute, just until you can smell the garlic and it turns golden. Add the flour and stir for about 3 minutes until the flour is well incorporated and the mixture starts to lightly brown. Very slowly pour the warmed milk mixture into the flour mixture, whisking constantly until all of the milk mixture is added, and the sauce is smooth. Bring to a gentle simmer and continue to cook, whisking frequently, until the mixture thickens. Add the parmesan in a few batches, whisking after each addition until the cheese is melted and smooth. Season with salt and pepper, and whisk in the parsley.
When the pasta is cooked, drain it, and then add it to the skillet with the sauce. Turn off the heat and toss (tongs are good for this), until the pasta is well coated with the sauce. Serve immediately with red pepper flakes, if desired.