Position a rack in the center of the oven and preheat the oven to 400ºF (205℃). Line a baking sheet with foil or baking paper, like I did, spray with cooking spray or lightly oil. Set aside.
Make 4-5 slits in each salmon fillet with a sharp knife. Dab both sides of the salmon dry with paper towels, and season both sides with salt and pepper.
Heat a small pan over medium-low heat. Melt the butter, then add minced garlic, paprika, onion powder, cayenne pepper, and parsley or basil. Stir for 30 seconds to a minute. Let this mixture sit for a little bit, about 5 minutes. Stir in the lemon juice.
Brush the salmon fillets with the mixture, covering every inch.
Bake until cooked through, 10-15 minutes, depending on the salmon's thickness and your preferred doneness. The salmon is perfectly cooked when the thickest part easily flakes with a fork.
Garnish immediately with lemon slices and serve.
