You will need two 9 x 13 pans. Place the bottoms of 12 rolls in each pan. Place ham (about 2 shaved slices or so) on the rolls. Cut the cheese slices into 4 parts and place 2 small pieces on each sandwich. Put the dinner roll tops on. In a sauce pan, mix butter, dijon mustard, worcestershire sauce, and dried onions. Wait until all butter is melted and then pour the melted mixture over the ham sandwiches (I know it sounds weird but TRUST me). Sprinkle the buns with poppy seeds and cover with foil. Let refrigerate overnight (If not able to wait, it is okay. They still taste great if made right away). Preheat oven to 350 and uncover sandwiches. Bake at 350 for 15-20 minutes and serve. They are great hot and even at room temperature Enjoy!
*I have made these with turkey also and they are good. Not as great as the ham, but they are good.