Cook the fettuccine or spaghetti according to package instructions until al dente. Drain and set aside.
In a large skillet over medium heat, melt the butter. Add the ground beef and cook until browned, breaking it apart with a spoon, about 5-7 minutes.
Stir in the minced garlic, Italian seasoning, and red pepper flakes (if using). Cook for an additional 1-2 minutes until the garlic is fragrant.
Pour in the beef broth and bring to a simmer. Let it cook for about 3-4 minutes to reduce slightly.
Lower the heat and stir in the heavy cream and Parmesan cheese. Mix until the cheese is melted and the sauce is creamy. Season with salt and pepper to taste.
Add the cooked pasta to the skillet and toss to coat in the sauce. Cook for another 2-3 minutes to heat through.
Serve immediately, garnished with chopped parsley.