Step 1

Preheat oven to 325 F.

Step 2

Slice your rolls in half horizontally.

Step 3

In a small saucepan, melt the butter.

Step 4

Whisk in the onion, mustard, poppy seeds, and Worcestershire sauce.

Step 5

Brush the butter mixture evenly over both the top (outside) and bottom half of the rolls.

Step 6

Layer the ham and Swiss slices over the bottom half of the rolls.

Step 7

Replace the top half of the rolls, and cover with foil.

Step 8

Bake for about 15-20 minutes, or until cheese is melted.

Step 9

Remove from oven, and serve warm.