1/2 c. soft butter, melted
2 tbsp. mustard
2 tbsp. onion, chopped (or equivalent dry minced onion)
1 tbsp. poppy seed
6 slices ham
6 slices Swiss cheese
6 buns (or 12 slices rye bread)

Mix butter, mustard, onion and poppy seed together and spread on both sides of the bun or bread. Add the ham and Swiss cheese and put the sandwich together. Bake at 375 degrees for 15 minutes.

Can be made ahead of time and frozen, then thaw before baking.