Preheat the oven to 350°F (175°C).
Prepare a baking dish by greasing it lightly or lining it with parchment paper.
Slice the slider rolls in half, keeping the tops and bottoms connected.
In a bowl, mix together the melted butter, Dijon mustard, garlic powder, and poppy seeds.
Lay half of the slider rolls in the prepared baking dish, cut side up.
Layer the slices of ham and cheese evenly over the bottom halves.
Place the top halves of the rolls on the layered filling.
Brush the butter mixture generously over the tops of the sliders.
Cover the baking dish with foil and bake for 15 minutes.
Remove the foil and bake for an additional 10 minutes until the tops are golden brown.
Let the sliders cool for a few minutes before serving.