Preheat your oven to 400F (200C) and line a baking sheet with parchment paper.

Pat the cod fillets dry with a paper towel. Season both sides evenly with salt and black pepper, then place them on the prepared baking sheet.

In a small bowl, whisk together the mayonnaise, half of the lemon juice, and half of the lemon zest. Brush this creamy mixture evenly over the top of each cod fillet.

In a separate bowl, toss the panko breadcrumbs, chopped parsley, remaining lemon zest, and olive oil until the crumbs are evenly moistened.

Press the breadcrumb mixture gently onto the top of each sauce-coated cod fillet.

Bake for 12 to 15 minutes, or until the fish is opaque and flakes easily with a fork. Serve hot with the remaining lemon juice squeezed over the top.