Bring a large pot of water to a boil and season with 1 tablespoon of salt. Add the fettuccine and cook for 6–7 minutes, or until just under al dente. Drain, reserving 2 cups of the pasta cooking water. Set aside.

While the pasta cooks, heat the olive oil in a large sauté pan over medium-high heat. Season the steak cubes evenly with kosher salt and black pepper. Add the steak to the pan in a single layer and cook undisturbed for 2–3 minutes. Flip and cook an additional 2–3 minutes, or until the internal temperature reaches approximately 155°F (medium). Remove the steak from the pan, transfer to a plate, and loosely cover with foil.

Add a small splash of water to the pan to loosen any browned residue, then discard the liquid. Return the pan to medium heat.

Add the heavy cream and 1 cup of the reserved pasta water to the pan. Bring to a gentle simmer. Add the cooked fettuccine and stir to combine. Allow the mixture to simmer for approximately 3 minutes, or until slightly thickened.

Stir in the Parmesan cheese until fully melted and incorporated. Add the spinach and sundried tomatoes and cook for 1 minute, or until the spinach has wilted. If the sauce becomes too thick, add additional pasta water in small increments to reach the desired consistency. Season with cracked black pepper to taste.

Divide the pasta among serving plates. Top with gorgonzola crumbles, the reserved steak, and drizzle with balsamic glaze. Serve immediately.