01 - Pat the salmon fillets dry with paper towels and season both sides generously with 1/2 teaspoon salt and 1/4 teaspoon black pepper.
02 - Heat olive oil in a large skillet over medium-high heat. Add salmon fillets skin-side down if using skin-on. Sear for 4 minutes, then flip and cook 2-3 minutes longer until golden and nearly cooked through. Remove salmon from skillet and set aside.
03 - Reduce heat to medium. Add butter to the same skillet and let melt. Sauté minced garlic and diced onion for 2-3 minutes until fragrant and translucent.
04 - Stir in sliced sun-dried tomatoes and cook for 1 minute to release their flavors.
05 - Pour in heavy cream and broth, scraping up any browned bits from the bottom of the pan. Bring mixture to a gentle simmer.
06 - Add grated Parmesan cheese and Italian seasoning. Stir continuously until cheese melts completely and sauce thickens slightly, approximately 2 minutes.
07 - Add baby spinach leaves and cook just until wilted, about 1 minute. Adjust seasoning with additional salt and pepper to taste.
08 - Return salmon fillets to the skillet, spooning sauce generously over each piece. Simmer gently for 2-3 minutes until salmon is cooked through. Serve hot, garnished with fresh basil leaves and lemon wedges if desired.