Dry the cod fillets thoroughly using paper towels to ensure the coating sticks well.
Brush each cod fillet with olive oil on both sides, then season with salt, pepper, and garlic powder.
Combine the grated Parmesan, panko breadcrumbs, lemon zest, and a pinch of salt in a shallow bowl and mix evenly.
Press each cod fillet into the Parmesan-panko mixture, making sure the crust sticks firmly.
Set the coated cod on a plate and allow it to rest for 3 to 5 minutes to help the crust bond.
Preheat your air fryer to 400°F (200°C) and let it warm up for 3 minutes.
Lightly spray the air fryer basket with cooking spray, then place the cod fillets in a single layer without overlapping.
Air fry the fillets for 6 minutes, then carefully flip them and continue cooking for another 4 to 5 minutes until the fish is opaque and flakes easily, and the crust turns golden brown.
While the cod rests for 2 minutes after cooking, mix the melted butter with a squeeze of fresh lemon juice.
Drizzle the lemon-butter sauce over the cod, sprinkle with chopped parsley, and serve with lemon wedges for an extra zing.