Season the fish and flavor with the lemon juice.
Melt the butter or margarine.
Brush either the grid of the broiling pan, or a piece of foil spread over the grid of the broiling pan (this saves time in washing-up) with butter or margarine.
Put the fish on the grid or foil, brush with butter or margarine and broil quickly for 2-3 minutes.
Turn and broil quickly for the same time on the other side, then lower the heat and cook for a few more minutes until the cod is tender.
Lift on to a hot dish, top with the parsley butter and garnish with sliced lemon and parsley.