Preheat your oven to 400 degrees Fahrenheit (200 degrees Celsius). Line a baking sheet with parchment paper for easy cleanup.
Pat the cod fillets dry using paper towels. This helps the sauce adhere better.
In a small bowl, whisk together the melted butter, minced garlic, lemon juice, and lemon zest.
Place the cod fillets on the prepared baking sheet. Season both sides lightly with salt and pepper.
Spoon the lemon garlic butter mixture evenly over the top of each cod fillet.
Bake for 12 to 15 minutes, depending on the thickness of the fish. The cod is done when it flakes easily with a fork and reaches an internal temperature of 145 degrees Fahrenheit (63 degrees Celsius).
Remove from the oven and sprinkle with fresh chopped parsley before serving immediately.
Notes
For extra moisture, you can place thin slices of lemon directly on top of the fillets before baking.
If your fillets are thinner than 1 inch, reduce the baking time to 10 minutes to prevent drying out.
You can add asparagus or green beans to the baking sheet during the last 10 minutes of cooking for a complete one-pan meal.