Spray Pam on the inside of your glass baking dish.
Slice horizontally through the rolls to separate the tops from the bottoms.
Place your bottom buns in your glass baking dish.
Spread 2 tablespoons of mayonnaise on the bottom buns.
Layer your ham then your cheese on the buns and cover with the tops.
Melt your butter in a pyrex measuring glass, then add 1 tbsp mayonnaise, your dijon mustard, Sorcestershire sauce, minced dried onion. Mix it all together and pour over the rolls.
Cover with foil and bake for about 20 minutes (check to see if the cheese is melted)
When the cheese is melted, and ham is warmed through, remove the foil for 5-10 minutes or until golden brown on top.