Preheat your oven to 425°F (220°C), ensuring the rack is positioned in the center.

In a medium-sized bowl, whisk together freshly squeezed lemon juice, olive oil, minced garlic, and Dijon mustard.

Place the skinless salmon fillets in your baking dish or skillet, and pour the marinade over them. Rub the marinade evenly across the fillets and sprinkle with ground black pepper and salt.

Transfer the dish into the preheated oven and bake for 10-15 minutes until the salmon flakes easily with a fork.

While the salmon bakes, heat a saucepan over medium heat and add unsalted butter. Once melted, sauté the additional minced garlic until fragrant.

Add heavy cream to the saucepan, stirring constantly until the mixture begins to simmer and thicken slightly.

Remove the saucepan from heat and stir in more freshly squeezed lemon juice and finely chopped parsley if desired.

Once the salmon is perfectly baked, remove it from the oven and let it sit for a couple of minutes. Drizzle the creamy lemon butter sauce generously over the fillets before garnishing with lemon slices and parsley.