Bring a large pot of salted water to a boil. Add the fettuccine and cook according to the package instructions until al dente. Once cooked, drain the pasta and set it aside, reserving about ½ cup of the pasta water for later.
While the pasta is cooking, heat 1 tablespoon of olive oil in a large skillet over medium heat. Season the salmon fillets with salt and pepper. Place them skin-side down in the skillet and cook for about 4 minutes on each side or until the salmon is just cooked through and flakes easily with a fork. Remove the salmon from the skillet and set aside.
Add the shrimp to the same skillet. Season with a pinch of salt and pepper and cook the shrimp for 2-3 minutes on each side until they turn pink and opaque. Remove from the skillet and set aside with the salmon.
In the same skillet, add the minced garlic and sauté for about 1 minute until fragrant, being careful not to burn it. Pour in the heavy cream and stir, scraping up any browned bits from the bottom of the pan for extra flavor.
Let the cream simmer gently for 3-4 minutes until it starts to thicken. Reduce the heat to low and gradually stir in the grated Parmesan cheese. Continue stirring until the cheese has melted completely and the sauce is smooth. If the sauce becomes too thick, add a splash of the reserved pasta water to loosen it up.
Flake the cooked salmon into bite-sized pieces. Add both the salmon and shrimp back into the skillet with the Alfredo sauce. Toss in the cooked fettuccine noodles and gently mix everything together until the pasta is well coated with the creamy sauce and seafood is evenly distributed.
Taste and adjust the seasoning with salt and pepper as needed.
Sprinkle chopped parsley over the top for a fresh, herbaceous finish. Serve immediately while warm and creamy.