Cook rotini pasta according to package instructions until al dente. Drain and set aside.
In a large skillet over medium heat, add olive oil and sauté the onion until soft.
Add garlic and cook for another 30 seconds until fragrant.
Add ground beef and cook until browned. Drain excess fat if necessary.
Pour in beef broth, heavy cream, and Parmesan cheese. Stir well.
Season with Italian seasoning, red pepper flakes, salt, and pepper.
Simmer for 5 minutes until the sauce thickens.
Add cooked rotini to the sauce, tossing to coat evenly.
Serve hot, garnished with fresh parsley.