Preheat the oven to 350°F. Place two sheets of aluminum foil side by side on a sheet pan (you'll use these to wrap and enclose the sandwiches).
Using a large serrated knife, slice the rolls in half horizontally, keeping the tops and bottoms connected. You'll end up with one large sheet of tops and one of bottoms, still intact.
12 Hawaiian sweet rolls
Place the bottom half of the rolls on the foil and layer the ham and cheese slices to fully cover them. Then, place the top half of the rolls over the meat and cheese.
8 oz Swiss cheese, sliced, 9 oz honey ham or regular thinly sliced ham
In a small saucepan over low heat, melt the butter with the mustard, dried onion, poppy seeds, and Worcestershire sauce. Pour 3/4 of the sauce over the top of the rolls.
4 tbsps butter, 1 tbsp honey mustard , 1 tbsp dried minced onion, 1 tbsp poppy seeds, 1 tsp Worcestershire sauce
Wrap the foil upwards around the sandwiches and bake on a sheet pan for 15 minutes.
Slightly rewarm the leftover butter sauce on the stove or in the microwave, then pour it evenly over the baked sandwiches.
Cut the sandwiches into individual rolls and serve them warm.