Preheat oven to 400 degrees. Combine butter, mustard, poppy seeds, onion and Worcestershire sauce. Set aside. Remove rolls intact from foil pans. Slice whole package of rolls horizontally through the middle. Return bottom layers to pans. Arrange ham and cheese on bottom layers and cover with top layer of rolls. Spread butter mixture over top of roll and put back on top of bottom rolls and cover tightly with aluminum foil. Bake 10 minutes and slice and serve.