Mix butter, mustard, Worcestershire sauce, poppy seeds, and dried onion. Separate the tops from the bottoms of the rolls, and place the bottom pieces into the prepared baking dish. Layer about half the ham onto the rolls. Arrange the Swiss cheese over the ham and top with remaining ham slices in a layer. Place the tops of the rolls onto the sandwiches. (At this point you can cover and refrigerate overnight) Before baking pour the butter mixture over the rolls.