Heat olive oil in a large skillet over medium heat.
Add minced garlic and sauté for 1-2 minutes until fragrant.
Stir in the chopped spinach and cook until wilted, about 3-4 minutes.
Pour in the heavy cream and bring to a simmer, stirring occasionally.
Add Parmesan cheese and nutmeg, stirring until cheese is melted and sauce is smooth.
Season the sauce with salt and pepper to taste.
Add salmon fillets to the sauce, skin side down, and spoon sauce over them.
Cover the skillet and cook for 5-7 minutes, or until salmon is cooked through.
Serve immediately, garnished with additional Parmesan if desired.