Try and purchase fillets that are roughly the same texture. This ensures that they all cook at the same temperature and you don't end up with any undercooked of dry pieces. The foil will prevent the fish from sticking to the bottom. In the event that you don't have foil, lightly brush the bottom of the pan with olive oil or cooking spray. Take 1-1/2 cups of bread crumbs (regular if you want smooth-textured cod, panko for extra crispy) and mix in 1 teaspoon sea salt, cracked black pepper,  1/3 cup chopped parsley, 1/4 cup chopped green onions, 1 teaspoon garlic powder, and any other desired spices. Toss the mixture so that the ingredients are mixed in evenly and set aside.  This breadcrumb mixture is easily customized, as the only "essential" ingredients are the breadcrumbs and the salt. If you want new seasonings, you can't go wrong with a teaspoon of chili powder, paprika, and/or cayenne for a hotter fish. For an herb mixture, try 1 tsp dried oregano, rosemary, thyme, and/or basil. Chop the butter in small cubes to help it melt faster, and work the microwave in intervals of 30 seconds or less. You don't need the butter to be hot, just melted into a liquid. Mix in the juice from 1 large lemon once it is melted. Dip each fillet in the butter, coating both sides, then move it to the breadcrumb mixture. Lightly press the fish into the breadcrumbs so that it is coated completely, then set in the baking dish. Once all the fish is in the pan, pour any remaining butter mixture over the fillets. The fish should be flaky and moist when removed. and it will feel firm. If the inside is shiny and translucent, cook them for another 2-3 minutes. Garnish with a lemon wedge and a sprig of fresh parsley and serve. Cod has a mild flavor that makes it easy to adapt. This means you can customize the dish to your liking with a few easy tweaks.  For a low-cal version, cut the butter and breadcrumb mixtures in half. Simply drizzle the butter on top of the fish and sprinkle your breadcrumbs only on the top of the fish. Toss 2-3 chopped tomatoes, 4 cloves of garlic, and one sliced onion with a tablespoon of olive oil and surround the fish with the vegetables when cooking for an easy side-dish to go with the fish. Substitute breadcrumbs for 1/2 cup of flour for a lighter coating on your cod.

Summary:
Rinse, clean, and dry your cod fillets. Pre-heat your oven to 425 and line a baking sheet with aluminum foil. Mix your breadcrumbs in with seasoning in a small bowl. Melt 4 tablespoons of butter in the microwave. Coat the fish in the butter mixture, then the breadcrumbs. Cook the fish for 12-15 minutes. Try out several variations on the dish to suit your liking.