Bring a large pot of salted water to boil over high heat. Add fettuccine pasta and cook according to package instructions until al dente. Reserve 1 cup of pasta water before draining.
While pasta cooks, melt butter in a large skillet over medium heat. Add minced garlic and sauté for 1-2 minutes until fragrant, being careful not to brown the garlic.
Pour heavy cream into the skillet and let it simmer for 5-8 minutes, stirring occasionally, until it reduces slightly and begins to thicken.
Add half of the parmesan cheese to the cream mixture. Whisk constantly until the cheese melts completely and the sauce becomes smooth and creamy.
Add the drained fettuccine to the skillet with the alfredo sauce. Toss well to coat the pasta completely. Add the remaining parmesan cheese and toss again.
If the sauce seems too thick, gradually add reserved pasta water, 2-3 tablespoons at a time, until you reach the desired consistency. Season with salt and pepper to taste.
Serve immediately, garnished with fresh Italian parsley if desired. The pasta is best enjoyed while hot and creamy.
