Preheat your oven to 400°F (200°C). Line a baking dish or sheet pan with foil or parchment paper.
In a small bowl, whisk together melted butter, honey, Dijon mustard, whole grain mustard, garlic powder, paprika, salt, pepper, and lemon juice until well combined.
Place the salmon fillets in the prepared baking dish, skin-side down if using.
Spoon or brush the honey mustard butter mixture evenly over each fillet.
Bake for 12–15 minutes, or until the salmon flakes easily with a fork and reaches an internal temperature of 145°F (63°C).
For extra caramelization, broil on high for 2–3 minutes at the end, watching closely to prevent burning.
Remove from the oven, garnish with fresh herbs and lemon slices, and serve warm