- Preheat your oven to 350°F (175°C). 
- Place the bottom halves of the rolls in a 9x13-inch baking dish. 
- Layer the ham evenly over the bottom halves, then top each with a slice of cheese. 
- Place the tops of the rolls over the cheese. 
- In a bowl, whisk together the melted butter, Dijon mustard, Worcestershire sauce, poppy seeds, and onion powder. 
- Pour the butter mixture evenly over the sandwiches. 
- Cover the dish with foil and bake for 15 minutes. 
- Remove foil and bake for another 5 minutes, or until tops are slightly crispy and golden. 
- Serve warm and try not to eat half the pan alone. No judgment if you do.