Cook the Pasta: Bring a large pot of generously salted water to a boil. Once boiling, add the fettuccine or spaghetti. Cook according to the package instructions until al dente, usually about 8-10 minutes. Reserve 1 cup of the pasta cooking water, then drain the remaining water and set the pasta aside.
Prepare the Garlic Butter Sauce: In a large skillet, melt the butter over medium heat. Once melted, add the minced garlic and sauté for 1-2 minutes, stirring frequently until the garlic is fragrant and lightly golden. Be cautious to avoid burning the garlic, as it can turn bitter.
Create the Creamy Base: Gradually pour in the heavy cream while stirring continuously. Allow the mixture to come to a gentle simmer, cooking for about 3-5 minutes, or until the sauce has slightly thickened, stirring occasionally.
Incorporate the Cheese: Slowly add the grated Parmesan cheese to the skillet, whisking continuously until the cheese has fully melted and the sauce is creamy and smooth. If the sauce appears too thick, gradually mix in a small amount of the reserved pasta water until your desired consistency is reached.
Season the Creamy Sauce: Next, add the red pepper flakes (if you're using them), lemon zest, salt, and freshly cracked black pepper to taste. Mix well to ensure all flavors are evenly distributed.
Combine Pasta and Sauce: Add the drained pasta to the skillet with the creamy sauce. Gently toss the pasta in the sauce until it's evenly coated. Allow it to heat through for an additional minute to combine the flavors.
Serve: Once heated, remove the skillet from the heat. Serve the pasta in bowls, garnished with a generous sprinkle of chopped fresh parsley and additional Parmesan cheese if desired.
Notes
For an appealing presentation, use a large serving platter and twirl the pasta into nests; sprinkle with chopped parsley and serve with a side of lemon wedges for added color and flavor.