Preheat oven to 180°C (355°F). Heat the butter and oil in a large non-stick frying pan. Add the onion, potato and garlic and cook for 10 minutes or until tender. Add the brandy and cream and cook for 3–4 minutes or until thickened. Remove from the heat and stir through the lemon rind, chives, fish, salt and pepper.
Spoon the mixture into a 5 cup-capacity (1.25L) ovenproof dish. Place the bread and extra butter in a bowl and toss to coat. Arrange on top of the fish mixture and bake for 15–20 minutes or until the bread is golden and crispy.