Step 1

Chop onion very finely, and put it into a pan with a stick of butter over medium heat. Let it cook for several minutes or until the onions are mostly cooked and translucent. Add mustard, Worcestershire, and poppy seeds. Stir together and remove from heat.

Step 2

Lay out two long sheets of tin foil on a cookie sheet -- one horizontally and one vertically. At the center, begin building the sandwiches by slicing the rolls in half and coating the bottom layer with a layer of the sauce reserving ⅓ c. for the top. Add a generous layer of cheese and a generous layer of ham. Put the tops of the rolls on and pour the remaining butter over the whole thing. Wrap the foil over the sandwiches and refrigerate for 30 minutes to let the butter soak in or freeze in a foil pan to bake later. Bake in a preheated 350 degree oven for 20 minutes.