In a large pot of salted boiling water, cook pasta per package directions until hard. Drain and put aside.
Flavor steak generously with salt and pepper. In an exceedingly large skillet over medium-high heat, cook steak until your required doneness, 3 minutes per side for medium-rare. Transfer to a plate to let rest, 10 minutes, then thinly slice.
In the meantime, make Alfredo sauce: Add butter to the skillet and let melt, then add garlic and cook until fragrant, one minute.
Mixer in flour and cook for one minute more, then add milk and simmer until thickened, five minutes, and then add parsley and Parmesan. Add tomatoes and cook down 2 minutes.
Add cooked pasta to the sauce and toss until coated, then add spinach and toss until wilted.
Top with sliced steak and drizzle with balsamic glaze.