1-First Step: Prep the fish and oven Start by preheating the oven to 400°F. Lightly grease a baking dish or line a baking sheet with parchment paper if you prefer easier cleanup. Pat the 1 1/2 pounds cod loin fillet dry with paper towels, then season both sides lightly with salt and pepper. Drying the fish helps it bake up nicely instead of steaming.

2-Second Step: Build the flavor base Place the cod in the prepared baking dish in a single layer. Drizzle the fish with 2 tablespoons olive oil and rub it gently over the top. This helps the seasonings stay in place and adds a little richness. Next, sprinkle the minced garlic evenly over the fish so every piece gets some flavor.

3-Third Step: Add the lemon and butter Pour the 4 tablespoons lemon juice over the cod. Then scatter the 1/4 cup diced butter around and on top of the fish. Arrange the 1 small lemon, sliced over the fillet. As the cod bakes, the butter melts with the lemon juice and garlic to form a simple butter sauce that coats the fish beautifully.

4-Fourth Step: Bake until flaky Place the dish in the oven and bake uncovered for about 12 to 18 minutes, depending on the thickness of your cod. Thin fillets may cook faster, while thicker pieces need a few extra minutes. Start checking around the 10-minute mark so you do not overcook it. The cod should turn opaque and flake easily with a fork when done.

5-Fifth Step: Check for doneness If you use a thermometer, the thickest part of the fish should reach 145°F. That is the safest temperature for cooked cod. If the fish flakes easily but still looks moist in the center, it is ready to come out. Be careful not to leave it in too long, since cod can dry out quickly.

6-Final Step: Finish and serve Spoon some of the melted lemon garlic butter sauce from the pan over the fish before serving. Add chopped parsley on top if you like a fresh, colorful finish. Serve immediately while the cod is warm and tender. This dish goes well with rice, roasted potatoes, green beans, or a simple salad.