Preheat your oven to 400°F (200°C). Lightly oil a 9x13 inch baking dish.

Melt ½ cup of unsalted butter over medium-low heat in a small saucepan. Add 4 minced garlic cloves and cook for about 60 seconds until fragrant. Whisk in 3 tbsp of fresh lemon juice and half of the chopped parsley.

Pat the salmon fillet dry with paper towels. Place it in the prepared baking dish. Drizzle with 1 tbsp of olive oil and sprinkle with ½ tsp of kosher salt and ¼ tsp of black pepper.

Pour three-quarters of the garlic butter sauce over the salmon and arrange thin slices of lemon on top.

Bake in the preheated oven for 12-15 minutes until the salmon is opaque and flakes easily.

Remove from the oven, drizzle with remaining garlic butter sauce, and garnish with remaining parsley. Serve immediately.