01 - Bring a large pot of salted water to a boil. Cook the fettuccine according to package instructions until al dente. Reserve 1/2 cup pasta water, then drain and set aside.
02 - While the pasta cooks, pat salmon fillets dry with paper towels. Season both sides generously with salt and freshly ground black pepper.
03 - Heat olive oil in a large skillet over medium-high heat. Add salmon fillets and sear for 3-4 minutes per side, or until just cooked through and golden brown. Transfer to a plate and cover loosely with foil to keep warm.
04 - In the same skillet, reduce heat to medium. Melt butter, add shallot, and sauté for 1 minute until softened. Add garlic and cook until fragrant, about 30 seconds.
05 - Pour in white wine if using and let it simmer for 1-2 minutes, scraping up any browned bits from the bottom of the skillet.
06 - Stir in heavy cream, lemon zest, and lemon juice. Simmer gently for 2-3 minutes until slightly thickened. Whisk in Parmesan cheese until completely smooth. Season with salt and pepper to taste.
07 - Flake salmon into large chunks. Add drained fettuccine and salmon to the skillet. Toss gently to coat, adding reserved pasta water as needed to loosen the sauce. Sprinkle with chopped parsley and serve immediately with extra Parmesan and lemon wedges if desired.