Ham And Swiss Sliders

I've combined two different recipes to make one that I like for these sliders.

12 King's Hawaiian rolls
Good deli ham
Swiss cheese

For the sauce:
1 stick butter
minced onion
1 Tablespoon mustard
1 Tablespoon worcestershire sauce
1 Tablespoon brown sugar

Melt all the sauce ingredients together and pour on prepared sandwiches in a baking dish. Bake at 350 degrees for 10-12 minutes.