Preheat the oven to 350°F.
Lightly coat a 9x13-inch baking dish with nonstick cooking spray.
In a medium bowl, combine the melted unsalted butter, honey mustard, minced dried onion, and Worcestershire sauce.
Stir the butter mixture until all ingredients are fully combined.
Slice the Hawaiian rolls in half horizontally, separating the tops from the bottoms while keeping the rolls connected if possible.
Set the top half of the rolls aside.
Place the bottom half of the Hawaiian rolls into the prepared baking dish.
Arrange the sliced honey baked ham evenly over the roll bottoms.
Place the Swiss cheese slices evenly over the ham.
If desired, repeat with an additional layer of ham and cheese for a fuller sandwich.
Place the top half of the Hawaiian rolls over the ham and cheese layers.
Pour the prepared butter sauce evenly over the tops of the rolls.
Cover the baking dish tightly with aluminum foil.
Bake for 20 minutes, or until the sandwiches are heated through and the cheese begins to melt.
Remove the foil from the baking dish.
Continue baking for an additional 10 to 15 minutes, or until the tops are lightly golden and the cheese is fully melted.
Remove the baking dish from the oven.
Allow the sandwiches to rest for several minutes before slicing or separating.
Serve warm.