Heat a large skillet over high heat. Add thinly sliced steak and sear for 3-4 minutes until browned on one side, then flip and sear for another 3-4 minutes.

Remove the steak from the skillet and set aside. Reduce heat to medium and add butter. Once melted, add garlic and red pepper flakes, sautéing until garlic is fragrant.

Stir in spaghetti or linguine, then add beef broth. Bring to a simmer and cook for about 10 minutes, stirring occasionally, until pasta is al dente.

Add grated Parmesan cheese and stir until melted and creamy, then return steak to the skillet, mixing well to coat the pasta.

Let rest off the heat for 2-3 minutes before serving, allowing flavors to meld.