Ham and swiss sliders

1 package Hawaiian rolls
18 slices deli ham
12 slices Swiss cheese
1 stick butter
1 tablespoon yellow mustard
1/2 tablespoon Worcestershire sauce
1/2 tablespoon dried minced onion
1/4 teaspoon pepper
Parmesan cheese
Dried parsley

Preheat oven to 350 degrees. Cover 9-by-13 pan with foil and spray with cooking spray. Remove rolls from package and cut entire slab in half lengthwise. Place bottom half in foil covered pan. Layer with half of the ham, then Swiss cheese, then remaining ham. Add top half of rolls. Melt butter and whisk in remaining ingredients except Parmesan cheese and parsley. Pour evenly over rolls. Cover with foil and let sit 5-10 minutes. Bake covered for 20 minutes. Uncover and bake additional 5 minutes. Sprinkle with Parmesan and parsley. Slice into individual sliders and serve warm.