Bring a large pot of salted water to a rolling boil. Add the fettuccine and cook until extremely al dente, about 2 minutes less than package instructions. Reserve a cup of pasta water before draining.

In a large skillet over medium-high heat, melt 1 tablespoon of butter. Add the shrimp, seasoning with kosher salt and pepper. Sear for 1-2 minutes on each side, until pink and opaque. Remove and keep warm.

In the same skillet, melt the remaining butter over medium heat. Add the minced garlic and sauté for 30 seconds. Whisk in flour to form a roux, then gradually add heavy cream and whole milk.

Continue whisking over medium heat until the sauce thickens slightly, about 2-3 minutes. Stir in Parmesan until melted. Adjust thickness with reserved pasta water if needed.

Return the fettuccine and shrimp to the skillet, tossing to coat with the sauce. Heat over low for another minute.

Transfer to serving plates and garnish with chopped parsley. Serve immediately, ideally with garlic bread or a salad.