Preheat your oven to 350°F (175°C).

Slice the slider buns in half horizontally, keeping the tops and bottoms intact.

Place the bottom halves of the slider buns into a 9x13-inch baking dish.

Layer each bun bottom with a slice of ham and a slice of Swiss cheese.

Place the slider bun tops on top of the ham and cheese layers.

In a small bowl, mix the melted butter, Dijon mustard, Worcestershire sauce, minced onion, garlic powder, and poppy seeds (if using).

Using a pastry brush or spoon, evenly spread the butter mixture over the tops of the sliders.

Cover the baking dish with aluminum foil and bake in the preheated oven for 15 minutes.

Remove the foil and bake for an additional 5 minutes, or until the tops are golden and the cheese is melted.

Remove from the oven, let cool slightly, and serve warm.