Preheat the oven to 350°F (175°C). Lightly grease a 9x13-inch baking dish.

Without separating the rolls, slice the entire slab of Hawaiian rolls in half horizontally. Place the bottom half in the prepared baking dish.

Layer the ham evenly over the bottom rolls, then top with the Swiss cheese slices. Place the top half of the rolls over the cheese.

In a small bowl, whisk together the melted butter, Dijon mustard, Worcestershire sauce, poppy seeds, onion powder, garlic powder, salt, and black pepper.

Spoon or brush the butter mixture evenly over the tops of the rolls, making sure it seeps into the edges and across the surface.

Cover the baking dish with foil and bake for 15 minutes. Remove the foil and bake for 5 to 10 more minutes, until the tops are golden and the cheese is melted.

Let the sliders cool for a few minutes, then cut and serve warm.