1/2 c. butter, softened
1/2 c. mustard
2 tbsp. grated onion
1 tbsp. poppy seeds
8 slices ham
8 slices Swiss cheese
8 buns

Mix together first four ingredients. Spread mixture on both sides of buns, place ham and cheese on bun. Wrap each bun in aluminum foil. Bake 20 minutes at 350 degrees.