Cut the rolls in half. Spread mayo on the bottom half and place in a 9 x 13 baking dish.
Place 1-2 slices of ham and 1/2 slice swiss cheese on top of each roll. Put the top half on.
In a medium size bowl, melt the butter. Then whisk poppy seeds, mustard, onion powder, and Worcestershire sauce. Pour over rolls.
Cover with foil and return to the refrigerator for at least 10 minutes or up to two days.
Bake covered at 350 for 20 minutes, or until the cheese is melted.
Uncover and cook for two more minutes, or until the tops are brown.