Bring a large pot of salted water to a boil. Add the fettuccine pasta and cook according to package instructions until al dente. Drain and set aside.
While the pasta cooks, season the steak bites with kosher salt and black pepper.
Heat olive oil and 1 tablespoon of butter in a large skillet over medium-high heat until hot but not smoking.
Add the steak bites in a single layer and cook without stirring for 2-3 minutes to sear one side.
Stir and continue cooking for another 2-3 minutes until the steak bites are browned on all sides and cooked to your desired doneness. Remove steak bites from the skillet and set aside, covering loosely with foil to keep warm.
In the same skillet, reduce heat to medium and add the remaining 2 tablespoons of butter.
Add 2 cloves of minced garlic and sauté for about 30 seconds until fragrant, being careful not to burn the garlic.
Pour in the heavy cream and bring to a gentle simmer. Cook for 2-3 minutes until slightly thickened.
Add the grated Parmesan cheese and crushed red pepper flakes. Stir until the cheese melts and the sauce is smooth.
Add the cooked fettuccine pasta to the skillet and toss to coat evenly with the garlic parmesan sauce.
Add the remaining 2 cloves of minced garlic and chopped fresh parsley to the pasta and toss again.
Serve the garlic parmesan pasta on plates and top with the warm steak bites.
Garnish with additional parsley if desired and serve immediately.