Preheat the oven to 350°F (175°C). Lightly grease a medium baking dish or baking sheet.
Melt the butter in a medium saucepan over medium heat.
Add the fresh lemon juice, salt, black pepper, dried parsley, and minced garlic. Stir until combined.
Bring the mixture to a gentle simmer. Cook for several minutes, stirring occasionally, until fragrant and slightly reduced. Avoid aggressively boiling or browning the butter.
Pat the cod fillets dry with paper towels and arrange them in a single layer in the prepared baking dish.
Spoon approximately half of the lemon garlic butter evenly over the fish.
Sprinkle the cod with lemon pepper seasoning.
Cover the baking dish loosely with foil and bake the Fantastic Lemon Butter Fillet for approximately 15–20 minutes, depending on the thickness of the fillets.
The cod is ready when it turns opaque and flakes easily at its thickest point. For food safety, fish should reach an internal temperature of 145°F (63°C).
Spoon the remaining warm garlic lemon butter over the baked cod and serve immediately.