In a large pot, fill with water and bring it to a rolling boil over high heat. Add kosher salt and the fettuccine noodles. Cook for 6-7 minutes until they are just under al dente, then reserve 2 cups of the pasta water, drain the noodles, and set aside.

In a sauté pan over medium-high heat, add olive oil and let it heat until shimmering. Carefully place the steak cubes in the pan, searing them for 2-3 minutes until golden brown. Flip and cook for an additional 3-4 minutes, reaching 155°F for medium doneness. Remove steak and cover with foil.

Pour in the reserved pasta water, scraping up any browned bits. Let it simmer for 1-2 minutes to concentrate flavors.

Reduce heat to low and stir in heavy cream followed by the deglazed pasta water. Allow to simmer gently for 3-5 minutes, then add the cooked fettuccine and toss to coat.

Mix in Parmesan cheese, torn spinach, and sundried tomatoes. Cook until spinach wilts, about 2-3 minutes. Add more reserved pasta water if the sauce is too thick.

Plate the pasta, crumble gorgonzola over and finish with a drizzle of balsamic glaze.