Ham with Chablis and Mustard

The best way I know to serve leftover ham hot. Place thickish slices of good ham in a gratin dish you can bring to the table. Cover it with a béchamel sauce made from a roux using equal quantities of flour and butter, to which you add as much good dry white wine (not really chablis) as you feel you can afford. Make up the remainder of the sauce with milk or cream in the usual way, season