Slice the rolls in half so you have a section of tops and section of bottoms. Try to keep them together as one unit. Put the bottom sections of rolls in prepared pan.
Evenly layer half of the ham over the rolls.
Evenly layer the cheese.
Even layer the other half of the ham.
Add the top section of rolls and set aside.
Sauce
Put the butter into a bowl and heat in the microwave until melted (about 1 minute).
Whisk together the mustard, poppy seeds, onion, Worcestershire sauce, salt, pepper.
Evenly pour the butter mixture over the rolls. Use a spatula to spread over the tops.
Cover with aluminum foil and allow rolls to stand for about 5-10 minutes.
Bake covered for about 20 minutes or until cheese is melted. Uncover and bake about 3 to 5 minutes.
Slice into individual sliders and serve immediately.