Preheat your oven to 400°F (200°C).

In a food processor, combine the shelled pistachios, breadcrumbs, olive oil, garlic powder, onion powder, paprika, salt, and pepper. Pulse until the mixture resembles coarse crumbs. Set aside.

Pat the cod fillets dry with paper towels. Place them on a baking sheet lined with parchment paper. Drizzle lemon juice over the fillets and season them with salt and pepper.

Evenly distribute the pistachio mixture over the top of each cod fillet, pressing gently to adhere.

Place the baking sheet in the preheated oven and bake for 12-15 minutes, or until the cod is opaque and flakes easily with a fork.

In a small bowl, whisk together the mayonnaise, minced garlic, lemon juice, Dijon mustard, salt, and pepper until smooth. Adjust seasoning to taste.

Once the cod is cooked, remove it from the oven. Serve the baked cod with a generous dollop of zesty garlic aioli on the side. Garnish with lemon zest and chopped parsley.