Sprinkle the fish with salt and pepper and toss in the flour to coat on all sides.
Heat 80g butter in a large heavy frying pan. Place the fish in one layer and brown for 3-5 minutes. Turn with a spatula and cook another 5 minutes, or until just cooked through.
Push the fish to one side of the frying pan and add the diced shallots. Cover and cook 3 more minutes.
Transfer the fish to a warm serving plate. Add the brandy and cream and cook about 2 minutes over high heat. Stir in the remaining butter. Briefly return the fish to the frying pan to coat with the sauce and serve.