Chop garlic very finely for a mellow and well-incorporated flavor in the sauce., Use room-temperature butter before melting to ensure a smoother sauce that coats the fish well., Monitor baking time closely after 10 minutes to avoid drying out the cod., Rotate baking dish halfway if oven heat is uneven for consistent cooking., Use a quick-read thermometer to ensure perfect doneness (145°F/63°C)., Butter-garlic sauce can be prepared up to two days ahead and refrigerated., Raw fillets can be frozen in the marinade for up to one month; thaw thoroughly before baking., Leftover cooked fish should be stored in an airtight container in the refrigerator for 1–2 days and reheated gently at low temperature with some reserved sauce., Panko breadcrumbs with lemon zest and melted butter can be sprinkled on top before baking to add a crunchy finishing touch., Olive oil can substitute butter for a lighter, dairy-free alternative., Adding capers and a splash of dry white wine to the butter sauce adds a tangy, briny flavor., Optional broiling for 1–2 minutes at the end can provide a golden finish—watch carefully to avoid burning.