If rolls are not cut, cut in half and place the bottoms on a baking sheet. Place a piece of ham and cheese on each bottom and place roll top in each piece of cheese.
In a sauce pan, mix together butter, brown sugar, Dijon mustard, Worcestershire sauce, onion powder and poppy seeds. Brush over rolls.
Cover the sandwiches with foil and bake for 10 minutes. When time is up, remove the foil and bake uncovered for an additional 5 minutes.
Best when served warm but are excellent reheated in oven as well.