Peel garlic and cut into thin plates. Wash parsley, dry, chop. Mix garlic, olive oil, salt and pepper, put half of the mixture in the form of refractory, place the cod fillets on top and put the remaining butter, remove the cover and marinate for 30 minutes in the refrigerator. Preheat oven to 200 degrees Celsius. Cook cod for 10 minutes, cover with foil and cook for another 10-12 minutes.