Preheat the oven to 180°C bake. Line a baking dish or roasting tray with baking paper.
Slice the bread rolls horizontally without separating the individual rolls, creating one connected top layer and one connected bottom layer.
In a small bowl, combine the mayonnaise, mustard, garlic powder, and onion powder.
Spread half of the mayonnaise mixture over the bottom layer of buns and the remaining half over the cut side of the top layer.
Layer the ham evenly over the bottom buns.
Place the Swiss cheese slices over the ham, ensuring the filling is well covered.
Bake the bottom half of the buns with the filling for 5–8 minutes, or until the cheese begins to soften and melt.
Meanwhile, combine the melted butter, Worcestershire sauce, chives, salt, pepper, and optional poppy seeds.
Remove the tray from the oven and place the top layer of buns over the filling.
Spoon or brush the butter mixture evenly over the tops of the buns.
Cover loosely with foil and bake for 10–15 minutes, or until the sliders are heated through and the tops are lightly golden.
If desired, remove the foil during the last few minutes of baking for extra colour.
Slice into individual sliders and serve warm.