Preheat oven to 350°F and lightly grease a 9x13-inch baking dish.
Slice the entire pack of Hawaiian rolls in half horizontally without separating them, and place the bottom half in the prepared baking dish.
Layer the ham and Swiss cheese evenly over the bottom half of the rolls, then place the top half of the rolls over the cheese.
In a small bowl, whisk together the melted butter, Dijon mustard, poppy seeds, dried onion, and Worcestershire sauce until well combined.
Pour the butter mixture evenly over the tops of the rolls, making sure to brush it to cover all surfaces.
Cover the dish with aluminum foil and bake for 15 minutes, then remove the foil and bake for an additional 5 minutes until the tops are golden brown.
Let cool for 5 minutes, then slice into individual sliders and serve warm.