Place the monkfish cubes in a large flameproof casserole or dutch oven and pour in the white wine. Add enough water just to cover the fish. Bring to a boil, then cover, reduce heat and simmer for 30 minutes. Preheat the oven to 450F. Remove the fish from the casserole with a slotted spoon and drain on paper towels. Strain the cooking liquid into a saucepan and reduce it by one-third. In a medium saucepan melt the butter over moderate heat and whisk in the flour. Cook for 2 minutes. Stir in 1/2 cup of the reduced cooking liquid and the crÅme fraöche. Boil until thickened, about 5 minutes. Season with salt and pepper. If the sauce is too thick, add a little of the reduced cooking liquid. Place the pieces of monkfish in a large shallow ovenproof dish. Pour over the sauce and sprinkle with the grated cheese. Bake for 15-20 minutes until golden brown.
