Slice rolls in half horizontally; place bottom half in a greased 9x13 pan.
Layer ham and cheese on the bottom half, then top with the other half of rolls.
Mix butter, mustard, Worcestershire, onion powder, and poppy seeds. Brush over rolls.
Cover with foil and bake 20 minutes. Remove foil; bake 5–7 more minutes until golden.
Slice sliders and serve warm.
Notes
Make-Ahead Tips- Refrigerate: Assemble, cover tightly, refrigerate up to 24 hours. Bake before serving.
- Freeze: Wrap tightly in foil + plastic wrap; freeze up to 2 months. Thaw overnight or bake from frozen (add 10–15 min).