Preheat oven to 400°F. Line a rimmed baking sheet with parchment and lightly oil it.
Pat salmon dry. Season both sides with 0.25 teaspoon salt and 0.25 teaspoon pepper (from the measured amounts). Place fillets skin-side down on the prepared sheet.
In a bowl, whisk Dijon, honey, lemon zest, lemon juice, garlic powder, and olive oil until smooth.
In a separate bowl, combine chopped pistachios and panko with the remaining 0.5 teaspoon salt and 0.25 teaspoon pepper.
Brush the Dijon mixture over the tops of the salmon. Press the pistachio mixture onto the coated tops to form an even crust.
Bake until the salmon flakes easily and the crust is lightly golden, 10 to 12 minutes depending on thickness. For extra color, broil for 1 minute at the end.
Rest 2 minutes. Garnish with parsley and serve with extra lemon if desired.
Notes
For even crunch, chop pistachios finely but not to a powder. If your fillets are thinner than 1 inch, begin checking for doneness at 9 minutes.