Preheat oven to 400℉ and lightly spray a 9X13 baking dish.
In a medium bowl, whisk together butter, dijon mustard, Worcestershire, poppy seeds, and dried onion and set aside.
If rolls are not already separated, separate the tops from the bottoms of the rolls and layer the bottoms in the baking dish.
Layer half of the ham onto the rolls and add a layer of gouda. Repeat.
Place the tops of the rolls onto the sandwiches. Pour the butter mixture evenly over the rolls.
Bake in the preheated oven for about 20 minutes or until the rolls are toasted and the cheese is melted.
Allow to cool slightly before slicing into individual rolls through the ham and cheese layers.
