01 - Preheat oven to 400°F (200°C). Lightly grease a baking dish large enough to fit the cod fillets in a single layer.
02 - Pat the cod fillets dry with paper towels and place them in the prepared baking dish.
03 - In a small bowl, whisk together melted butter, olive oil, lemon juice, lemon zest, garlic, parsley, salt, and pepper.
04 - Pour the lemon butter sauce evenly over the cod fillets.
05 - Bake in the preheated oven for 15–20 minutes, or until the cod is opaque and flakes easily with a fork.
06 - Garnish with lemon slices and extra parsley before serving.