Remove the rolls from the package, keep together and slice horizontally. Prepare a large piece of heavy duty foil, with plenty of extra to wrap the finished rolls, on the counter and place the bottom half of the rolls on the foil. Carefully set the top half aside. Layer the ham and cheese on the lower half of the rolls. Place the top half of the rolls over the ham and cheese portion. Melt the butter add poppy seeds, onion flakes and mustard - whisk to blend. With a pastry brush, brush the mixture over the rolls. It will drip down through the rolls and the edges. Wrap the rolls in the foil. At this point to can bake right away or you can refrigerate until you are ready to serve. Preheat your oven to 350 degrees and bake the rolls 20 - 30 minutes or until they are hot and gooey. Serve immediately.