Place parchment in huge jelly roll pan (or two large baking pans with sides).
Slice the top of each roll and place each bottom in the jelly roll/baking pan.
Layer the ham and cheese on each roll.
Replace the tops of each roll.
Combine the butter, poppy seeds, mustard, Worcestershire, and onion powder; mix well.
Brush the sauce over the tops of the rolls.
Cover the entire pan with foil and bake at 350° for 30 minutes or until the cheese melts.
Uncover the pan and cook for 2 additional minutes. Serve warm.
Notes
Low Carb Version: With half a low carb hot dog bun or my low carb sprouted dinner roll, each hamarama should be approximately 8 net carbs. Nutritional information is given with the recipe using the store bought, White rolls.