Cook the pasta according to package instructions in a large pot of salted boiling water until al dente. Reserve 1/2 cup of pasta water, then drain the pasta and set aside.
In a large skillet over medium heat, melt the butter. Add the minced garlic and red pepper flakes (if using), and sauté for about 1 minute until fragrant.
Add the ground beef to the skillet, breaking it apart with a spatula. Cook until browned and cooked through, about 5-7 minutes. Season with Italian seasoning, salt, and pepper.
Add the cooked pasta to the skillet with the beef and garlic butter. Toss to combine, adding reserved pasta water a little at a time until the desired consistency is reached.
Remove from heat and stir in the grated Parmesan cheese until melted and well combined. Adjust seasoning if necessary.
Serve immediately, garnished with chopped parsley.