01 - Preheat the oven to 400°F. Lightly grease a baking dish large enough to hold the cod fillets in a single layer.
02 - Pat the cod fillets dry with paper towels and arrange them in the prepared baking dish.
03 - In a small bowl, whisk together the melted butter, olive oil, lemon juice, lemon zest, minced garlic, parsley, salt, and pepper.
04 - Pour the lemon butter mixture evenly over the cod fillets.
05 - Top each fillet with a lemon slice.
06 - Bake for 15–20 minutes, or until the cod flakes easily with a fork and is opaque throughout.
07 - Remove from the oven, garnish with additional parsley, and serve immediately.