Sole Florentine

6 tablespoons unsalted butter 1 tablespoon chopped shallot 2 tablespoons flour 1 cup half-and-half or 1 cup light cream 1 teaspoon sugar 2 (10 ounce) boxes[...]

2 lbs skinless sole fillets (any firm mild white fish may be substituted such as orange roughy or flounder) 1/2 cup madeira wine or 1/2 cup dry sherry[...]