Preheat your oven to 400°F (200°C). Line a baking dish with parchment paper or lightly oil it.
Place the cod fillets in the dish. Pat them dry with a paper towel—this helps the butter stick.
In a small bowl, mix the melted butter, olive oil, lemon juice, lemon zest, and garlic.
Pour the lemon butter mixture evenly over the cod.
Sprinkle with salt and pepper.
Bake for 12–15 minutes or until the fish flakes easily with a fork.
Top with chopped parsley and serve immediately.