Preheat the oven to 350 degrees Fahrenheit.
Melt the butter in the microwave. Add the melted butter, dijon mustard, Worcestershire sauce, dried parsley, and onion powder to a small bowl. Mix to combine and set aside.
4 tbsp Unsalted butter, 1 tbsp Dijon mustard, 1 tsp Worcestershire sauce, 2 tsp Dried parsley, 1/2 tsp Onion powder
Remove the Hawaiian sweet rolls from their package. Using a sharp knife, cut through the middle of the entire dozen, so you end up with the top of the buns separate from the bottoms of the buns.
1 package Sweet Hawaiian rolls
Place the bottoms of the rolls in a 11×17 baking dish.
Layer half of the ham on the bottoms. Next, layer half the swiss cheese. Repeat with the remaining ham and cheese.
12 slices Deli ham, 12 slices Swiss cheese
Place the tops of the Hawaiian rolls on top of the ham and cheese.
Using a pastry brush, apply the butter mixture to the tops of the rolls. Cover with aluminum foil.
Place them into the oven and bake for 20-25 minutes.
Remove the foil and continue to bake for another 5-10 minutes until the rolls have browned up a bit and the swiss cheese is melty.
Remove them from the oven. Cut them into individual sliders and serve immediately.