Tenderize cube steak if needed and season both sides with salt and pepper.
Boil pasta in salted water according to package instructions. Reserve 1/2 cup pasta water, then drain.
In a large skillet, heat olive oil and butter over medium-high heat.
Sear the cube steak for 2–3 minutes on each side until browned. Remove and let rest.
In the same skillet, add onion and garlic. Cook until softened.
Stir in tomato paste if using, then add beef broth and bring to a simmer.
Pour in heavy cream and whisk until smooth. Season with Italian seasoning and red pepper flakes if desired.
Slice the steak into strips and return to the skillet. Simmer for 5–7 minutes until tender.
Add cooked pasta and Parmesan cheese to the skillet. Toss to coat and use reserved pasta water as needed to loosen the sauce.
Garnish with chopped parsley and serve hot.