Heat oven to 350° F.
Slice the Hawaiian rolls in half so you have the bottoms and the tops. Place the bottom halves in a 13"x9" baking dish. They will fit snugly.
Layer the ham on the rolls, evenly. You should have 2-3 layers of thinly sliced ham.
Layer the Swiss cheese over the ham. You should get 2 layers of the cheese slices.
Place the tops on the rolls.
In a small saucepan, heat the butter, Worcestershire sauce, dried onion, Dijon, and poppy seeds. When melted, stir well and remove from heat. Spoon over the tops of the rolls, being sure to get the sauce on all of the rolls. Stir as you do this so they all get some of the onion and poppy seeds on them.
Cover with foil and bake for 15 minutes. Then remove the foil and bake for another 10 to 15 minutes, or until the cheese in the center has melted, and the rolls have turned light golden in color.
Slice in between each roll and serve hot or warm.