Bring a large pot of generously salted water to a boil. Add the pasta and cook according to package directions until al dente.
Before draining, reserve about 1/3 cup of the pasta cooking water. Drain the pasta and set it aside.
Melt the butter in a large skillet over medium-low heat. Add the minced garlic and cook for about 30–60 seconds, stirring frequently, until fragrant.
Pour in the heavy cream and add the Italian seasoning, salt, black pepper, and red pepper flakes if using. Stir well and bring the sauce to a gentle simmer.
Reduce the heat to low. Gradually add the Parmesan cheese, stirring continuously until it melts and the sauce becomes smooth and creamy.
Add the drained pasta directly to the skillet. Toss until every strand or piece is evenly coated in the Parmesan sauce.
If the sauce is too thick, add reserved pasta water a tablespoon at a time until it reaches your preferred consistency.
Taste and adjust the salt and pepper as needed. Sprinkle with fresh parsley and additional Parmesan, then serve immediately.