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, worcestershire sauce, onion powder, garlic powder and poppy seeds. Wait until all butter is melted and then brush the melted mixture over the ham sandwiches. Cover with foil and let sit in fridge for 1 hour or over night. (If you want to bake them right away, you can also.) Preheat oven to 375 and bake for 15 minutes or until cheese is melted. Serve. They are great hot and even at room temperature Enjoy!