|⅓||cup butter, melted|
|2||tablespoons prepared mustard|
|1||small chopped onion|
|1||tablespoon poppy seeds|
|6||slices Swiss or American cheese|
Combine butter, mustard, onion, and poppy seeds. Spread on inside of hamburger buns. Place 1 slice ham and 1 slice cheese on each bun. Spread sauce on top of buns. Heat in oven on cookie sheet 15 minutes at 350 degrees.