Preheat your oven to 400°F (200°C).
Line a baking sheet with parchment paper or lightly grease it with cooking spray.
In a small bowl, whisk together the maple syrup, Dijon mustard, olive oil, garlic powder, salt, and black pepper until well combined.
Place the salmon fillet on the prepared baking sheet, skin-side down.
Brush the maple mixture generously over the salmon, ensuring it is evenly coated.
Sprinkle the chopped pistachios over the top of the salmon, pressing them gently into the glaze.
Bake in the preheated oven for 15-20 minutes, or until the salmon flakes easily with a fork and is cooked through.
Remove from the oven and let it rest for a few minutes. Garnish with fresh parsley before serving.