- Cut rolls in half and spread bottom half of rolls with horseradish sauce. 
- Layer ham on top of horseradish and then layer cheese on top of that. 
- Replace top half of the rolls on the layered ham and cheese, and place in a large baking dish. 
- Whisk together mustard, butter, onion powder and Worcestershire sauce and drizzle over rolls. 
- Sprinkle with poppy seeds. Cover with foil and let sit for fifteen minutes. 
- Bake at 350 degrees for 8 minutes, remove foil and cook for another 2 minutes until browned. Serve.