Sprinkle shallots in 25 cm skillet (use pyrosyran, non-stick finish, enamel or stainless (not aluminum)). Sprinkle fillets with salt and pepper. Fold in half; arrange in skillet. Add wine, lemon juice and reserved grape liquid. Heat to boiling; reduce heat. Cover and simmer until fillets flake easily, 4 to 5 minutes. Remove fillets with slotted spatula to ovenproof platter. Keep warm while preparing sauce. Add grapes to liquid in skillet. Heat to boiling; reduce heat. Simmer uncovered 3 minutes. Remove grapes with slotted spoon. Heat liquid in skillet to boiling; boil until reduced to 1 cup. Melt 2 tablespoons butter. Stir in flour. Stir flour mixture, a small amount at a time, into reduced liquid. Cook over low heat, stirring constantly, until thickened. Remove from heat. Stir in cream. Heat to boiling. Add 2 tablespoons butter; stir until melted. Drain excess liquid from platter if necessary. Spoon sauce over fillets. Set oven control to broil and/or 550'. Broil fillets just until sauce is glazed, about 3 minutes. Garnish with grapes.