Begin by setting your oven to 400°F (204°C) to ensure it reaches the ideal temperature before baking. Using thawed cod fillets is recommended for the best texture, but if necessary, frozen fillets can be used, though they may require a slightly longer cooking time.

Pat each fillet dry with paper towels to remove excess moisture. This step is crucial for achieving a flaky, tender texture. Arrange the fillets in a single layer in a 9x13-inch baking dish, ensuring they are evenly spaced for uniform cooking.

In a small saucepan over low heat or a microwave-safe bowl, melt the butter until completely liquefied. Remove from heat and stir in the fresh lemon juice and zest, whisking until well combined. This citrus-infused butter will add brightness and depth of flavor to the cod.

Generously brush the melted lemon butter over the fillets, ensuring an even coating. Sprinkle each piece with garlic powder, sea salt, and black pepper. Flip the fillets and repeat the process, ensuring both sides are fully coated with the butter mixture and seasonings. This double-layered approach enhances the overall flavor and ensures each bite is perfectly seasoned.

Place the baking dish in the preheated oven and bake for 12 to 15 minutes. The cooking time will depend on the thickness of the fillets. The cod is fully cooked when it reaches an internal temperature of 135-140°F (57-60°C) and easily flakes with a fork. The flesh should appear opaque and tender.

Once removed from the oven, immediately sprinkle the fillets with freshly chopped parsley to add a pop of color and an extra layer of freshness. Serve the cod hot, paired with your favorite side dishes, to enjoy its delicate, buttery flavor at its peak.