In a big pot of salted boiling-water, cook the pasta according to package instructions until al-dente. Drain & put aside.
Coat both sides of steak with oil & season liberally with pepper and salt. In a large-skillet over medium-high heat, cook steak till your preferred doneness for 4minutes each side for medium-rare. Transfer to a plate to allow remainder for 10minutes, then finely-slice.
Meanwhile, create alfredo-sauce: Add butter to skillet & let melt, then add garlic & cook till fragrant about a minute.
Whisk in flour and cook for a few minute, then add milk & simmer until thickened for 5minutes. Add parmesan and parsley and season with pepper and salt. Add tomatoes and cook-down for 2minutes.
Add cooked-pasta to sauce & toss till tender, then add spinach and toss till wilted.
Top with sliced-steak & drizzle with balsamic-glaze.