Bring a large pot of salted water to a boil and cook fettuccine according to package directions until al dente.
Season salmon fillets and shrimp with salt, pepper, and smoked paprika.
Heat olive oil in a large skillet over medium-high heat. Sear salmon for 4 minutes per side until golden and cooked through, then remove and flake into large chunks.
In the same skillet, sear shrimp for 2 minutes per side until pink and opaque, then remove and set aside.
Lower heat to medium and melt butter in the skillet. Add minced garlic and sauté for 1 minute until fragrant.
Pour in heavy cream and bring to a gentle simmer. Whisk in grated Parmesan cheese until the sauce thickens.
Stir in fresh spinach and allow to wilt into the sauce.
Add the cooked pasta, seared shrimp, and flaked salmon back into the skillet. Toss gently to coat with the sauce.
Garnish with fresh parsley and serve immediately.