Football Food: Hawaiian Sweet Roll Ham Sandwiches

This is one of those recipes I've seen floating about, but I didn't try it out until some of my coworkers were raving about the recipe at work.  They were right, it's DELICIOUS.  It makes 12 little mini ham sandwiches....perfect for a football watching party, AND you can make it in advance, then pop it in the oven when your guest arrive.  Win.  Win.  The recipe is originally from the blog beyerbeware.
Hawaiian Sweet Roll Sandwiches
Ingredients:  1 pkg 12 Hawaiian Sweet Rolls, 1 onion (grated), 1 stick of butter, 3 T Dijon mustard, 2 t. Worcestershire sauce, 3 t. poppy seeds, 1/2 pound shaved ham, 8 slices of Swiss cheese. 
Instructions: 
1.  Melt butter in a skillet and add onion, mustard, Worcestershire sauce and poppy seeds.  Simmer for several minutes. 
2.  Slice rolls length wise.   Place on foil lined baking dish.   Place half the onion mix on the bottom of the rolls.  Top with ham and then cheese. Place stop on rolls. 
3.  Top remaining rolls with spread.  Cover with aluminum foil and place in fridge until you are read to bake/eat. 
4.  Bake covered by foil for 20 minutes at 350 degrees.