Bring a large pot of water to a rolling boil. Add 1 tablespoon kosher salt. Add 12 oz spaghetti and cook until just shy of al dente according to package instructions (about 8–9 minutes). Reserve 1 cup of pasta cooking water, then drain the pasta and toss with 1 tablespoon olive oil to prevent sticking. Set aside.

Salmon

Season salmon

Pat the salmon fillets dry with paper towels. Sprinkle both sides with 1 tsp kosher salt, 1 tsp freshly ground black pepper, and 1 tsp lemon zest. Let sit at room temperature while you start the sauce, about 5 minutes.

Sear salmon

Heat a large nonstick or stainless-steel skillet over medium-high heat and add 1 tablespoon olive oil. When the oil shimmers, place salmon skin-side down. Press gently for 10 seconds to prevent curling. Cook undisturbed until the skin is crisp and the salmon is about two-thirds cooked through, about 4–5 minutes depending on thickness. Flip and cook the top side for 1–2 minutes for medium (internal temp ~125°F/52°C). Remove salmon to a plate and tent with foil. Reserve pan juices for the sauce.

Sauce & Vegetables

Sauté aromatics

Reduce heat to medium and in the same skillet add 2 tablespoons unsalted butter. Add 3 minced garlic cloves and 1 finely chopped shallot. Sauté until aromatic and softened, about 1–2 minutes, scraping up browned bits from the salmon.

Deglaze

Pour in 1 cup dry white wine (or chicken broth) to deglaze the pan. Use a wooden spoon to scrape any browned bits from the bottom. Let the liquid simmer and reduce by about half, 3–4 minutes.

Build cream sauce

Lower heat to medium-low and stir in 1 cup heavy cream. Bring to a gentle simmer, then add 1 cup grated Parmesan cheese in two additions, stirring until melted and smooth. If sauce becomes too thick, add a few tablespoons of reserved pasta water to reach desired consistency.

Add vegetables & season

Stir in 1 cup halved cherry tomatoes and 3 cups baby spinach. Cook until spinach wilts and tomatoes soften, 1–2 minutes. Add 2 tablespoons lemon juice, 1/4 tsp red pepper flakes, and season with salt and freshly ground black pepper to taste. If sauce needs thinning, add reserved pasta water 1–2 tablespoons at a time.

Combine pasta and sauce

Add the drained spaghetti to the skillet and toss to coat evenly in the cream sauce. Add a splash of reserved pasta water if necessary to help the sauce cling to the noodles. Stir in additional 1–2 tablespoons grated Parmesan if desired. Taste and adjust seasoning.

Finish & Serve

Place the seared salmon fillets on top of portions of sauced spaghetti. Spoon a little extra sauce and tomatoes over the salmon. Garnish with 2 tablespoons chopped fresh parsley and serve with lemon wedges on the side. Serve immediately.

Notes: If you prefer flaked salmon mixed into the pasta, flake the cooked fillets into large pieces and gently fold into the noodles instead of placing whole fillets on top.