Preheat the oven to 400°F (200°C). Line a baking sheet with aluminum foil and lightly spray or oil it.
In a small bowl, combine the olive oil, chopped parsley, grated Parmesan, minced garlic, salt, and ground black pepper; mix until evenly combined.
Pat the salmon fillets dry with paper towels and place them skin-side down on the prepared baking sheet.
Evenly spread the Parmesan-parsley mixture over the top of each salmon fillet.
Cover the fillets loosely with aluminum foil and bake for 15 minutes, or until the salmon flakes easily with a fork and is opaque throughout.
Remove the foil, serve immediately with lemon slices, and optionally sprinkle additional grated Parmesan if desired.