Prep the steak: Pat the steak dry.
Season both sides generously with salt and black pepper. Let it rest at room temperature for 20–30 minutes while you prep everything else.
Boil the pasta: Bring a large pot of salted water to a boil. Cook fettuccine until just shy of al dente.
Reserve 1 cup of pasta water, then drain.
Pan-sear the steak: Heat a large skillet over medium-high. Add 1 tablespoon olive oil and 1 tablespoon butter. When hot and shimmering, add the steak.
Sear 3–4 minutes per side for medium-rare (adjust to your preference). Transfer to a plate, tent with foil, and rest 5–10 minutes.
Make the garlic base: Lower the heat to medium. In the same skillet, add 2 tablespoons butter.
Stir in the minced garlic and cook 30–60 seconds until fragrant. Don’t brown it.
Build the Alfredo sauce: Pour in heavy cream and bring to a gentle simmer. Whisk in Parmesan until smooth.
Add a splash of broth or pasta water if it’s too thick. Season with salt, pepper, and a pinch of red pepper flakes if using.
Melt in the Gorgonzola: Add the crumbled Gorgonzola and stir until creamy. Taste and adjust seasoning.
The sauce should be glossy, rich, and slightly tangy.
Add spinach (optional): Stir in spinach and cook 1–2 minutes until just wilted. Add lemon zest for brightness.
Toss with pasta: Add the drained pasta to the skillet. Toss to coat, loosening with reserved pasta water as needed for a silky texture.
Slice the steak: Slice against the grain into thin strips.
For extra flavor, pour any resting juices into the sauce.
Finish and serve: Plate the Gorgonzola Alfredo pasta. Top with sliced steak. Drizzle with a small amount of balsamic glaze, then garnish with parsley and a little extra Parmesan.
Serve immediately.