Heat a large skillet over medium heat and add a splash of olive oil. Once shimmering, gently add the salmon fillets skin-side down. Cook for 4-5 minutes until the skin is crispy and the salmon is opaque about halfway up. Flip and cook for another 3-4 minutes until fully cooked through. Remove from the skillet and set aside, letting it rest as you prepare the sauce.

In the same skillet, add a little more olive oil if needed, then toss in minced garlic. Sauté for about 30 seconds until fragrant, stirring continuously to prevent burning. Pour in the heavy cream, bringing it to a gentle simmer while scraping up any flavor bits from the salmon that remain in the pan.

Stir in the freshly grated Parmesan cheese until it melts smoothly into the creamy mixture. As the sauce thickens, add the fresh spinach, cooking for 2-3 minutes until just wilted.

Carefully return the cooked salmon to the skillet, along with a drizzle of fresh lemon juice. Gently stir to coat the salmon in the rich, velvety sauce.

Spoon the creamy salmon mixture onto plates and garnish with extra Parmesan or freshly chopped herbs if desired.