Cook the pasta: Bring a large pot of salted water to a boil. Add the pasta and cook according to package directions until al dente. Pro Tip: Reserve about 1/4 cup of the starchy pasta water before draining; this will help create a creamier sauce.
Sauté the garlic: While the pasta is cooking, melt 1/2 cup of butter in a large skillet over medium heat. Add the minced garlic and red pepper flakes (if using) and sauté for 1-2 minutes, or until fragrant. Be careful not to burn the garlic, as this will impart a bitter taste.
Create the sauce: Stir in the heavy cream and Parmesan cheese. Cook, stirring constantly, until the cheese is melted and the sauce is smooth and creamy.
Combine pasta and sauce: Add the drained pasta to the skillet with the sauce. Stir to coat the pasta evenly. Add 2 tablespoons of the reserved pasta water, one tablespoon at a time, to thin the sauce to your desired consistency. Season with salt and pepper to taste.
Serve: Garnish with extra Parmesan cheese and fresh parsley (if using). Serve immediately and enjoy!